diff --git a/src/land/engine/ArcanistLandEngine.php b/src/land/engine/ArcanistLandEngine.php
index 3e15f7d6..692946eb 100644
--- a/src/land/engine/ArcanistLandEngine.php
+++ b/src/land/engine/ArcanistLandEngine.php
@@ -1,1581 +1,1619 @@
 <?php
 
 abstract class ArcanistLandEngine
   extends ArcanistWorkflowEngine {
 
   private $sourceRefs;
   private $shouldHold;
   private $shouldKeep;
   private $shouldPreview;
   private $isIncremental;
   private $ontoRemoteArgument;
   private $ontoArguments;
   private $intoEmptyArgument;
   private $intoLocalArgument;
   private $intoRemoteArgument;
   private $intoArgument;
   private $strategyArgument;
   private $strategy;
 
   private $revisionSymbol;
   private $revisionSymbolRef;
 
   private $ontoRemote;
   private $ontoRefs;
   private $intoRemote;
   private $intoRef;
   private $intoEmpty;
   private $intoLocal;
 
   private $localState;
   private $hasUnpushedChanges;
   private $pickArgument;
 
   final public function setOntoRemote($onto_remote) {
     $this->ontoRemote = $onto_remote;
     return $this;
   }
 
   final public function getOntoRemote() {
     return $this->ontoRemote;
   }
 
   final public function setOntoRefs($onto_refs) {
     $this->ontoRefs = $onto_refs;
     return $this;
   }
 
   final public function getOntoRefs() {
     return $this->ontoRefs;
   }
 
   final public function setIntoRemote($into_remote) {
     $this->intoRemote = $into_remote;
     return $this;
   }
 
   final public function getIntoRemote() {
     return $this->intoRemote;
   }
 
   final public function setIntoRef($into_ref) {
     $this->intoRef = $into_ref;
     return $this;
   }
 
   final public function getIntoRef() {
     return $this->intoRef;
   }
 
   final public function setIntoEmpty($into_empty) {
     $this->intoEmpty = $into_empty;
     return $this;
   }
 
   final public function getIntoEmpty() {
     return $this->intoEmpty;
   }
 
   final public function setPickArgument($pick_argument) {
     $this->pickArgument = $pick_argument;
     return $this;
   }
 
   final public function getPickArgument() {
     return $this->pickArgument;
   }
 
   final public function setIntoLocal($into_local) {
     $this->intoLocal = $into_local;
     return $this;
   }
 
   final public function getIntoLocal() {
     return $this->intoLocal;
   }
 
   final public function setShouldHold($should_hold) {
     $this->shouldHold = $should_hold;
     return $this;
   }
 
   final public function getShouldHold() {
     return $this->shouldHold;
   }
 
   final public function setShouldKeep($should_keep) {
     $this->shouldKeep = $should_keep;
     return $this;
   }
 
   final public function getShouldKeep() {
     return $this->shouldKeep;
   }
 
   final public function setStrategyArgument($strategy_argument) {
     $this->strategyArgument = $strategy_argument;
     return $this;
   }
 
   final public function getStrategyArgument() {
     return $this->strategyArgument;
   }
 
   final public function setStrategy($strategy) {
     $this->strategy = $strategy;
     return $this;
   }
 
   final public function getStrategy() {
     return $this->strategy;
   }
 
   final public function setRevisionSymbol($revision_symbol) {
     $this->revisionSymbol = $revision_symbol;
     return $this;
   }
 
   final public function getRevisionSymbol() {
     return $this->revisionSymbol;
   }
 
   final public function setRevisionSymbolRef(
     ArcanistRevisionSymbolRef $revision_ref) {
     $this->revisionSymbolRef = $revision_ref;
     return $this;
   }
 
   final public function getRevisionSymbolRef() {
     return $this->revisionSymbolRef;
   }
 
   final public function setShouldPreview($should_preview) {
     $this->shouldPreview = $should_preview;
     return $this;
   }
 
   final public function getShouldPreview() {
     return $this->shouldPreview;
   }
 
   final public function setSourceRefs(array $source_refs) {
     $this->sourceRefs = $source_refs;
     return $this;
   }
 
   final public function getSourceRefs() {
     return $this->sourceRefs;
   }
 
   final public function setOntoRemoteArgument($remote_argument) {
     $this->ontoRemoteArgument = $remote_argument;
     return $this;
   }
 
   final public function getOntoRemoteArgument() {
     return $this->ontoRemoteArgument;
   }
 
   final public function setOntoArguments(array $onto_arguments) {
     $this->ontoArguments = $onto_arguments;
     return $this;
   }
 
   final public function getOntoArguments() {
     return $this->ontoArguments;
   }
 
   final public function setIsIncremental($is_incremental) {
     $this->isIncremental = $is_incremental;
     return $this;
   }
 
   final public function getIsIncremental() {
     return $this->isIncremental;
   }
 
   final public function setIntoEmptyArgument($into_empty_argument) {
     $this->intoEmptyArgument = $into_empty_argument;
     return $this;
   }
 
   final public function getIntoEmptyArgument() {
     return $this->intoEmptyArgument;
   }
 
   final public function setIntoLocalArgument($into_local_argument) {
     $this->intoLocalArgument = $into_local_argument;
     return $this;
   }
 
   final public function getIntoLocalArgument() {
     return $this->intoLocalArgument;
   }
 
   final public function setIntoRemoteArgument($into_remote_argument) {
     $this->intoRemoteArgument = $into_remote_argument;
     return $this;
   }
 
   final public function getIntoRemoteArgument() {
     return $this->intoRemoteArgument;
   }
 
   final public function setIntoArgument($into_argument) {
     $this->intoArgument = $into_argument;
     return $this;
   }
 
   final public function getIntoArgument() {
     return $this->intoArgument;
   }
 
   private function setLocalState(ArcanistRepositoryLocalState $local_state) {
     $this->localState = $local_state;
     return $this;
   }
 
   final protected function getLocalState() {
     return $this->localState;
   }
 
   private function setHasUnpushedChanges($unpushed) {
     $this->hasUnpushedChanges = $unpushed;
     return $this;
   }
 
   final protected function getHasUnpushedChanges() {
     return $this->hasUnpushedChanges;
   }
 
   final protected function getOntoConfigurationKey() {
     return 'arc.land.onto';
   }
 
   final protected function getOntoFromConfiguration() {
     $config_key = $this->getOntoConfigurationKey();
     return $this->getWorkflow()->getConfig($config_key);
   }
 
   final protected function getOntoRemoteConfigurationKey() {
     return 'arc.land.onto-remote';
   }
 
   final protected function getOntoRemoteFromConfiguration() {
     $config_key = $this->getOntoRemoteConfigurationKey();
     return $this->getWorkflow()->getConfig($config_key);
   }
 
   final protected function getStrategyConfigurationKey() {
     return 'arc.land.strategy';
   }
 
   final protected function getStrategyFromConfiguration() {
     $config_key = $this->getStrategyConfigurationKey();
     return $this->getWorkflow()->getConfig($config_key);
   }
 
   final protected function confirmRevisions(array $sets) {
     assert_instances_of($sets, 'ArcanistLandCommitSet');
 
     $revision_refs = mpull($sets, 'getRevisionRef');
     $viewer = $this->getViewer();
     $viewer_phid = $viewer->getPHID();
 
     $unauthored = array();
     foreach ($revision_refs as $revision_ref) {
       $author_phid = $revision_ref->getAuthorPHID();
       if ($author_phid !== $viewer_phid) {
         $unauthored[] = $revision_ref;
       }
     }
 
     if ($unauthored) {
       $this->getWorkflow()->loadHardpoints(
         $unauthored,
         array(
           ArcanistRevisionRef::HARDPOINT_AUTHORREF,
         ));
 
       echo tsprintf(
         "\n%!\n%W\n\n",
         pht('NOT REVISION AUTHOR'),
         pht(
           'You are landing revisions which you ("%s") are not the author of:',
           $viewer->getMonogram()));
 
       foreach ($unauthored as $revision_ref) {
         $display_ref = $revision_ref->newRefView();
 
         $author_ref = $revision_ref->getAuthorRef();
         if ($author_ref) {
           $display_ref->appendLine(
             pht(
               'Author: %s',
               $author_ref->getMonogram()));
         }
 
         echo tsprintf('%s', $display_ref);
       }
 
       echo tsprintf(
         "\n%?\n",
         pht(
           'Use "Commandeer" in the web interface to become the author of '.
           'a revision.'));
 
       $query = pht('Land revisions you are not the author of?');
 
       $this->getWorkflow()
         ->getPrompt('arc.land.unauthored')
         ->setQuery($query)
         ->execute();
     }
 
     $planned = array();
     $published = array();
     $not_accepted = array();
     foreach ($revision_refs as $revision_ref) {
       if ($revision_ref->isStatusChangesPlanned()) {
         $planned[] = $revision_ref;
       } else if ($revision_ref->isStatusPublished()) {
         $published[] = $revision_ref;
       } else if (!$revision_ref->isStatusAccepted()) {
         $not_accepted[] = $revision_ref;
       }
     }
 
     // See T10233. Previously, this prompt was bundled with the generic "not
     // accepted" prompt, but users found it confusing and interpreted the
     // prompt as a bug.
 
     if ($planned) {
       $example_ref = head($planned);
 
       echo tsprintf(
         "\n%!\n%W\n\n%W\n\n%W\n\n",
         pht('%s REVISION(S) HAVE CHANGES PLANNED', phutil_count($planned)),
         pht(
           'You are landing %s revision(s) which are currently in the state '.
           '"%s", indicating that you expect to revise them before moving '.
           'forward.',
           phutil_count($planned),
           $example_ref->getStatusDisplayName()),
         pht(
           'Normally, you should update these %s revision(s), submit them '.
           'for review, and wait for reviewers to accept them before '.
           'you continue. To resubmit a revision for review, either: '.
           'update the revision with revised changes; or use '.
           '"Request Review" from the web interface.',
           phutil_count($planned)),
         pht(
           'These %s revision(s) have changes planned:',
           phutil_count($planned)));
 
       foreach ($planned as $revision_ref) {
         echo tsprintf('%s', $revision_ref->newRefView());
       }
 
       $query = pht(
         'Land %s revision(s) with changes planned?',
         phutil_count($planned));
 
       $this->getWorkflow()
         ->getPrompt('arc.land.changes-planned')
         ->setQuery($query)
         ->execute();
     }
 
     // See PHI1727. Previously, this prompt was bundled with the generic
     // "not accepted" prompt, but at least one user found it confusing.
 
     if ($published) {
       $example_ref = head($published);
 
       echo tsprintf(
         "\n%!\n%W\n\n",
         pht('%s REVISION(S) ARE ALREADY PUBLISHED', phutil_count($published)),
         pht(
           'You are landing %s revision(s) which are already in the state '.
           '"%s", indicating that they have previously landed:',
           phutil_count($published),
           $example_ref->getStatusDisplayName()));
 
       foreach ($published as $revision_ref) {
         echo tsprintf('%s', $revision_ref->newRefView());
       }
 
       $query = pht(
         'Land %s revision(s) that are already published?',
         phutil_count($published));
 
       $this->getWorkflow()
         ->getPrompt('arc.land.published')
         ->setQuery($query)
         ->execute();
     }
 
     if ($not_accepted) {
       $example_ref = head($not_accepted);
 
       echo tsprintf(
         "\n%!\n%W\n\n",
         pht('%s REVISION(S) ARE NOT ACCEPTED', phutil_count($not_accepted)),
         pht(
           'You are landing %s revision(s) which are not in state "Accepted", '.
           'indicating that they have not been accepted by reviewers. '.
           'Normally, you should land changes only once they have been '.
           'accepted. These revisions are in the wrong state:',
           phutil_count($not_accepted)));
 
       foreach ($not_accepted as $revision_ref) {
         $display_ref = $revision_ref->newRefView();
         $display_ref->appendLine(
           pht(
             'Status: %s',
             $revision_ref->getStatusDisplayName()));
         echo tsprintf('%s', $display_ref);
       }
 
       $query = pht(
         'Land %s revision(s) in the wrong state?',
         phutil_count($not_accepted));
 
       $this->getWorkflow()
         ->getPrompt('arc.land.not-accepted')
         ->setQuery($query)
         ->execute();
     }
 
     $this->getWorkflow()->loadHardpoints(
       $revision_refs,
       array(
         ArcanistRevisionRef::HARDPOINT_PARENTREVISIONREFS,
       ));
 
     $open_parents = array();
     foreach ($revision_refs as $revision_phid => $revision_ref) {
       $parent_refs = $revision_ref->getParentRevisionRefs();
       foreach ($parent_refs as $parent_ref) {
         $parent_phid = $parent_ref->getPHID();
 
         // If we're landing a parent revision in this operation, we don't need
         // to complain that it hasn't been closed yet.
         if (isset($revision_refs[$parent_phid])) {
           continue;
         }
 
         if ($parent_ref->isClosed()) {
           continue;
         }
 
         if (!isset($open_parents[$parent_phid])) {
           $open_parents[$parent_phid] = array(
             'ref' => $parent_ref,
             'children' => array(),
           );
         }
 
         $open_parents[$parent_phid]['children'][] = $revision_ref;
       }
     }
 
     if ($open_parents) {
       echo tsprintf(
         "\n%!\n%W\n\n",
         pht('%s OPEN PARENT REVISION(S) ', phutil_count($open_parents)),
         pht(
           'The changes you are landing depend on %s open parent revision(s). '.
           'Usually, you should land parent revisions before landing the '.
           'changes which depend on them. These parent revisions are open:',
           phutil_count($open_parents)));
 
       foreach ($open_parents as $parent_phid => $spec) {
         $parent_ref = $spec['ref'];
 
         $display_ref = $parent_ref->newRefView();
 
         $display_ref->appendLine(
           pht(
             'Status: %s',
             $parent_ref->getStatusDisplayName()));
 
         foreach ($spec['children'] as $child_ref) {
           $display_ref->appendLine(
             pht(
               'Parent of: %s %s',
               $child_ref->getMonogram(),
               $child_ref->getName()));
         }
 
         echo tsprintf('%s', $display_ref);
       }
 
       $query = pht(
         'Land changes that depend on %s open revision(s)?',
         phutil_count($open_parents));
 
       $this->getWorkflow()
         ->getPrompt('arc.land.open-parents')
         ->setQuery($query)
         ->execute();
     }
 
     $this->confirmBuilds($revision_refs);
 
     // This is a reasonable place to bulk-load the commit messages, which
     // we'll need soon.
 
     $this->getWorkflow()->loadHardpoints(
       $revision_refs,
       array(
         ArcanistRevisionRef::HARDPOINT_COMMITMESSAGE,
       ));
   }
 
   private function confirmBuilds(array $revision_refs) {
     assert_instances_of($revision_refs, 'ArcanistRevisionRef');
 
     $this->getWorkflow()->loadHardpoints(
       $revision_refs,
       array(
         ArcanistRevisionRef::HARDPOINT_BUILDABLEREF,
       ));
 
     $buildable_refs = array();
     foreach ($revision_refs as $revision_ref) {
       $ref = $revision_ref->getBuildableRef();
       if ($ref) {
         $buildable_refs[] = $ref;
       }
     }
 
     $this->getWorkflow()->loadHardpoints(
       $buildable_refs,
       array(
         ArcanistBuildableRef::HARDPOINT_BUILDREFS,
       ));
 
     $build_refs = array();
     foreach ($buildable_refs as $buildable_ref) {
       foreach ($buildable_ref->getBuildRefs() as $build_ref) {
         $build_refs[] = $build_ref;
       }
     }
 
     $this->getWorkflow()->loadHardpoints(
       $build_refs,
       array(
         ArcanistBuildRef::HARDPOINT_BUILDPLANREF,
       ));
 
     $problem_builds = array();
     $has_failures = false;
     $has_ongoing = false;
 
     $build_refs = msortv($build_refs, 'getStatusSortVector');
     foreach ($build_refs as $build_ref) {
       $plan_ref = $build_ref->getBuildPlanRef();
       if (!$plan_ref) {
         continue;
       }
 
       $plan_behavior = $plan_ref->getBehavior('arc-land', 'always');
       $if_building = ($plan_behavior == 'building');
       $if_complete = ($plan_behavior == 'complete');
       $if_never = ($plan_behavior == 'never');
 
       // If the build plan "Never" warns when landing, skip it.
       if ($if_never) {
         continue;
       }
 
       // If the build plan warns when landing "If Complete" but the build is
       // not complete, skip it.
       if ($if_complete && !$build_ref->isComplete()) {
         continue;
       }
 
       // If the build plan warns when landing "If Building" but the build is
       // complete, skip it.
       if ($if_building && $build_ref->isComplete()) {
         continue;
       }
 
       // Ignore passing builds.
       if ($build_ref->isPassed()) {
         continue;
       }
 
       if ($build_ref->isComplete()) {
         $has_failures = true;
       } else {
         $has_ongoing = true;
       }
 
       $problem_builds[] = $build_ref;
     }
 
     if (!$problem_builds) {
       return;
     }
 
     $build_map = array();
     $failure_map = array();
     $buildable_map = mpull($buildable_refs, null, 'getPHID');
     $revision_map = mpull($revision_refs, null, 'getDiffPHID');
     foreach ($problem_builds as $build_ref) {
       $buildable_phid = $build_ref->getBuildablePHID();
       $buildable_ref = $buildable_map[$buildable_phid];
 
       $object_phid = $buildable_ref->getObjectPHID();
       $revision_ref = $revision_map[$object_phid];
 
       $revision_phid = $revision_ref->getPHID();
 
       if (!isset($build_map[$revision_phid])) {
         $build_map[$revision_phid] = array(
           'revisionRef' => $revision_ref,
           'buildRefs' => array(),
         );
       }
 
       $build_map[$revision_phid]['buildRefs'][] = $build_ref;
     }
 
     $log = $this->getLogEngine();
 
     if ($has_failures) {
       if ($has_ongoing) {
         $message = pht(
           '%s revision(s) have build failures or ongoing builds:',
           phutil_count($build_map));
 
         $query = pht(
           'Land %s revision(s) anyway, despite ongoing and failed builds?',
           phutil_count($build_map));
 
       } else {
         $message = pht(
           '%s revision(s) have build failures:',
           phutil_count($build_map));
 
         $query = pht(
           'Land %s revision(s) anyway, despite failed builds?',
           phutil_count($build_map));
       }
 
       echo tsprintf(
         "%!\n%s\n",
         pht('BUILD FAILURES'),
         $message);
 
       $prompt_key = 'arc.land.failed-builds';
     } else if ($has_ongoing) {
       echo tsprintf(
         "%!\n%s\n",
         pht('ONGOING BUILDS'),
         pht(
           '%s revision(s) have ongoing builds:',
           phutil_count($build_map)));
 
       $query = pht(
         'Land %s revision(s) anyway, despite ongoing builds?',
         phutil_count($build_map));
 
       $prompt_key = 'arc.land.ongoing-builds';
     }
 
     $workflow = $this->getWorkflow();
 
     echo tsprintf("\n");
     foreach ($build_map as $build_item) {
       $revision_ref = $build_item['revisionRef'];
       $revision_view = $revision_ref->newRefView();
 
       $buildable_ref = $revision_ref->getBuildableRef();
       $buildable_view = $buildable_ref->newRefView();
 
       $raw_uri = $buildable_ref->getURI();
       $raw_uri = $workflow->getAbsoluteURI($raw_uri);
       $buildable_view->setURI($raw_uri);
 
       $revision_view->addChild($buildable_view);
 
       foreach ($build_item['buildRefs'] as $build_ref) {
         $build_view = $build_ref->newRefView();
         $buildable_view->addChild($build_view);
       }
 
       echo tsprintf('%s', $revision_view);
       echo tsprintf("\n");
     }
 
     $this->getWorkflow()
       ->getPrompt($prompt_key)
       ->setQuery($query)
       ->execute();
   }
 
   final protected function confirmImplicitCommits(array $sets, array $symbols) {
     assert_instances_of($sets, 'ArcanistLandCommitSet');
     assert_instances_of($symbols, 'ArcanistLandSymbol');
 
     $implicit = array();
     foreach ($sets as $set) {
       if ($set->hasImplicitCommits()) {
         $implicit[] = $set;
       }
     }
 
     if (!$implicit) {
       return;
     }
 
     echo tsprintf(
       "\n%!\n%W\n",
       pht('IMPLICIT COMMITS'),
       pht(
         'Some commits reachable from the specified sources (%s) are not '.
         'associated with revisions, and may not have been reviewed. These '.
         'commits will be landed as though they belong to the nearest '.
         'ancestor revision:',
         $this->getDisplaySymbols($symbols)));
 
     foreach ($implicit as $set) {
       $this->printCommitSet($set);
     }
 
     $query = pht(
       'Continue with this mapping between commits and revisions?');
 
     $this->getWorkflow()
       ->getPrompt('arc.land.implicit')
       ->setQuery($query)
       ->execute();
   }
 
   final protected function getDisplaySymbols(array $symbols) {
     $display = array();
 
     foreach ($symbols as $symbol) {
       $display[] = sprintf('"%s"', addcslashes($symbol->getSymbol(), '\\"'));
     }
 
     return implode(', ', $display);
   }
 
   final protected function printCommitSet(ArcanistLandCommitSet $set) {
     $api = $this->getRepositoryAPI();
     $revision_ref = $set->getRevisionRef();
 
     echo tsprintf(
       "\n%s",
       $revision_ref->newRefView());
 
     foreach ($set->getCommits() as $commit) {
       $is_implicit = $commit->getIsImplicitCommit();
 
       $display_hash = $api->getDisplayHash($commit->getHash());
       $display_summary = $commit->getDisplaySummary();
 
       if ($is_implicit) {
         // NOTE: Mark commits with both a color and a character so the marking
         // survives copy/paste.
         echo tsprintf(
           "       ! <bg:yellow> %s </bg> %s\n",
           $display_hash,
           $display_summary);
       } else {
         echo tsprintf(
           "          %s  %s\n",
           $display_hash,
           $display_summary);
       }
     }
   }
 
   final protected function loadRevisionRefs(array $commit_map) {
     assert_instances_of($commit_map, 'ArcanistLandCommit');
     $api = $this->getRepositoryAPI();
     $workflow = $this->getWorkflow();
 
     $state_refs = array();
     foreach ($commit_map as $commit) {
       $hash = $commit->getHash();
 
       $commit_ref = id(new ArcanistCommitRef())
         ->setCommitHash($hash);
 
       $state_ref = id(new ArcanistWorkingCopyStateRef())
         ->setCommitRef($commit_ref);
 
       $state_refs[$hash] = $state_ref;
     }
 
     $force_symbol_ref = $this->getRevisionSymbolRef();
     $force_ref = null;
     if ($force_symbol_ref) {
       $workflow->loadHardpoints(
         $force_symbol_ref,
         ArcanistSymbolRef::HARDPOINT_OBJECT);
 
       $force_ref = $force_symbol_ref->getObject();
       if (!$force_ref) {
         throw new PhutilArgumentUsageException(
           pht(
             'Symbol "%s" does not identify a valid revision.',
             $force_symbol_ref->getSymbol()));
       }
     }
 
     $workflow->loadHardpoints(
       $state_refs,
       ArcanistWorkingCopyStateRef::HARDPOINT_REVISIONREFS);
 
     foreach ($commit_map as $commit) {
       $hash = $commit->getHash();
       $state_ref = $state_refs[$hash];
       $revision_refs = $state_ref->getRevisionRefs();
       $commit->setRelatedRevisionRefs($revision_refs);
     }
 
     // For commits which have exactly one related revision, select it now.
 
     foreach ($commit_map as $commit) {
       $revision_refs = $commit->getRelatedRevisionRefs();
 
       if (count($revision_refs) !== 1) {
         continue;
       }
 
       $revision_ref = head($revision_refs);
       $commit->setExplicitRevisionRef($revision_ref);
     }
 
     // If we have a "--revision", select that revision for any commits with
     // no known related revisions.
 
     // Also select that revision for any commits which have several possible
     // revisions including that revision. This is relatively safe and
     // reasonable and doesn't require a warning.
 
     if ($force_ref) {
       $force_phid = $force_ref->getPHID();
       foreach ($commit_map as $commit) {
         if ($commit->getExplicitRevisionRef()) {
           continue;
         }
 
         $revision_refs = $commit->getRelatedRevisionRefs();
 
         if ($revision_refs) {
           $revision_refs = mpull($revision_refs, null, 'getPHID');
           if (!isset($revision_refs[$force_phid])) {
             continue;
           }
         }
 
         $commit->setExplicitRevisionRef($force_ref);
       }
     }
 
     // If we have a "--revision", identify any commits which it is not yet
     // selected for. These are commits which are not associated with the
     // identified revision but are associated with one or more other revisions.
 
     if ($force_ref) {
       $force_phid = $force_ref->getPHID();
 
       $confirm_force = array();
       foreach ($commit_map as $key => $commit) {
         $revision_ref = $commit->getExplicitRevisionRef();
 
         if (!$revision_ref) {
           continue;
         }
 
         if ($revision_ref->getPHID() === $force_phid) {
           continue;
         }
 
         $confirm_force[] = $commit;
       }
 
       if ($confirm_force) {
 
         // TODO: Make this more clear.
         // TODO: Show all the commits.
 
         throw new PhutilArgumentUsageException(
           pht(
             'TODO: You are forcing a revision, but commits are associated '.
             'with some other revision. Are you REALLY sure you want to land '.
             'ALL these commits with a different unrelated revision???'));
       }
 
       foreach ($confirm_force as $commit) {
         $commit->setExplicitRevisionRef($force_ref);
       }
     }
 
     // Finally, raise an error if we're left with ambiguous revisions. This
     // happens when we have no "--revision" and some commits in the range
     // that are associated with more than one revision.
 
     $ambiguous = array();
     foreach ($commit_map as $commit) {
       if ($commit->getExplicitRevisionRef()) {
         continue;
       }
 
       if (!$commit->getRelatedRevisionRefs()) {
         continue;
       }
 
       $ambiguous[] = $commit;
     }
 
     if ($ambiguous) {
       foreach ($ambiguous as $commit) {
         $symbols = $commit->getIndirectSymbols();
         $raw_symbols = mpull($symbols, 'getSymbol');
         $symbol_list = implode(', ', $raw_symbols);
         $display_hash = $api->getDisplayHash($hash);
 
         $revision_refs = $commit->getRelatedRevisionRefs();
 
         // TODO: Include "use 'arc look --type commit abc' to figure out why"
         // once that works?
 
         // TODO: We could print all the ambiguous commits.
 
         // TODO: Suggest "--pick" as a remedy once it exists?
 
         echo tsprintf(
           "\n%!\n%W\n\n",
           pht('AMBIGUOUS REVISION'),
           pht(
             'The revision associated with commit "%s" (an ancestor of: %s) '.
             'is ambiguous. These %s revision(s) are associated with the '.
             'commit:',
             $display_hash,
             implode(', ', $raw_symbols),
             phutil_count($revision_refs)));
 
         foreach ($revision_refs as $revision_ref) {
           echo tsprintf(
             '%s',
             $revision_ref->newRefView());
         }
 
         echo tsprintf("\n");
 
         throw new PhutilArgumentUsageException(
           pht(
             'Revision for commit "%s" is ambiguous. Use "--revision" to force '.
             'selection of a particular revision.',
             $display_hash));
       }
     }
 
     // NOTE: We may exit this method with commits that are still unassociated.
     // These will be handled later by the "implicit commits" mechanism.
   }
 
   final protected function confirmCommits(
     $into_commit,
     array $symbols,
     array $commit_map) {
     $api = $this->getRepositoryAPI();
 
     $commit_count = count($commit_map);
 
     if (!$commit_count) {
       $message = pht(
         'There are no commits reachable from the specified sources (%s) '.
         'which are not already present in the state you are merging '.
         'into ("%s"), so nothing can land.',
         $this->getDisplaySymbols($symbols),
         $api->getDisplayHash($into_commit));
 
       echo tsprintf(
         "\n%!\n%W\n\n",
         pht('NOTHING TO LAND'),
         $message);
 
       throw new PhutilArgumentUsageException(
         pht('There are no commits to land.'));
     }
 
     // Reverse the commit list so that it's oldest-first, since this is the
     // order we'll use to show revisions.
     $commit_map = array_reverse($commit_map, true);
 
     $warn_limit = $this->getWorkflow()->getLargeWorkingSetLimit();
     $show_limit = 5;
     if ($commit_count > $warn_limit) {
       if ($into_commit === null) {
         $message = pht(
           'There are %s commit(s) reachable from the specified sources (%s). '.
           'You are landing into the empty state, so all of these commits '.
           'will land:',
           new PhutilNumber($commit_count),
           $this->getDisplaySymbols($symbols));
       } else {
         $message = pht(
           'There are %s commit(s) reachable from the specified sources (%s) '.
           'that are not present in the repository state you are merging '.
           'into ("%s"). All of these commits will land:',
           new PhutilNumber($commit_count),
           $this->getDisplaySymbols($symbols),
           $api->getDisplayHash($into_commit));
       }
 
       echo tsprintf(
         "\n%!\n%W\n",
         pht('LARGE WORKING SET'),
         $message);
 
       $display_commits = array_merge(
         array_slice($commit_map, 0, $show_limit),
         array(null),
         array_slice($commit_map, -$show_limit));
 
       echo tsprintf("\n");
 
       foreach ($display_commits as $commit) {
         if ($commit === null) {
           echo tsprintf(
             "  %s\n",
             pht(
               '< ... %s more commits ... >',
               new PhutilNumber($commit_count - ($show_limit * 2))));
         } else {
           echo tsprintf(
             "  %s %s\n",
             $api->getDisplayHash($commit->getHash()),
             $commit->getDisplaySummary());
         }
       }
 
       $query = pht(
         'Land %s commit(s)?',
         new PhutilNumber($commit_count));
 
       $this->getWorkflow()
         ->getPrompt('arc.land.large-working-set')
         ->setQuery($query)
         ->execute();
     }
 
     // Build the commit objects into a tree.
     foreach ($commit_map as $commit_hash => $commit) {
       $parent_map = array();
       foreach ($commit->getParents() as $parent) {
         if (isset($commit_map[$parent])) {
           $parent_map[$parent] = $commit_map[$parent];
         }
       }
       $commit->setParentCommits($parent_map);
     }
 
     // Identify the commits which are heads (have no children).
     $child_map = array();
     foreach ($commit_map as $commit_hash => $commit) {
       foreach ($commit->getParents() as $parent) {
         $child_map[$parent][$commit_hash] = $commit;
       }
     }
 
     foreach ($commit_map as $commit_hash => $commit) {
       if (isset($child_map[$commit_hash])) {
         continue;
       }
       $commit->setIsHeadCommit(true);
     }
 
     return $commit_map;
   }
 
   public function execute() {
     $api = $this->getRepositoryAPI();
     $log = $this->getLogEngine();
 
     $this->validateArguments();
 
     $raw_symbols = $this->getSourceRefs();
     if (!$raw_symbols) {
       $raw_symbols = $this->getDefaultSymbols();
     }
 
     $symbols = array();
     foreach ($raw_symbols as $raw_symbol) {
       $symbols[] = id(new ArcanistLandSymbol())
         ->setSymbol($raw_symbol);
     }
 
     $this->resolveSymbols($symbols);
 
     $onto_remote = $this->selectOntoRemote($symbols);
     $this->setOntoRemote($onto_remote);
 
     $onto_refs = $this->selectOntoRefs($symbols);
     $this->confirmOntoRefs($onto_refs);
     $this->setOntoRefs($onto_refs);
 
     $this->selectIntoRemote();
     $this->selectIntoRef();
 
     $into_commit = $this->selectIntoCommit();
     $commit_map = $this->selectCommits($into_commit, $symbols);
 
     $this->loadRevisionRefs($commit_map);
 
     // TODO: It's possible we have a list of commits which includes disjoint
     // groups of commits associated with the same revision, or groups of
     // commits which do not form a range. We should test that here, since we
     // can't land commit groups which are not a single contiguous range.
 
     $revision_groups = array();
     foreach ($commit_map as $commit_hash => $commit) {
       $revision_ref = $commit->getRevisionRef();
 
       if (!$revision_ref) {
         echo tsprintf(
           "\n%!\n%W\n\n",
           pht('UNKNOWN REVISION'),
           pht(
             'Unable to determine which revision is associated with commit '.
             '"%s". Use "arc diff" to create or update a revision with this '.
             'commit, or "--revision" to force selection of a particular '.
             'revision.',
             $api->getDisplayHash($commit_hash)));
 
         throw new PhutilArgumentUsageException(
           pht(
             'Unable to determine revision for commit "%s".',
             $api->getDisplayHash($commit_hash)));
       }
 
       $revision_groups[$revision_ref->getPHID()][] = $commit;
     }
 
     $commit_heads = array();
     foreach ($commit_map as $commit) {
       if ($commit->getIsHeadCommit()) {
         $commit_heads[] = $commit;
       }
     }
 
     $revision_order = array();
     foreach ($commit_heads as $head) {
       foreach ($head->getAncestorRevisionPHIDs() as $phid) {
         $revision_order[$phid] = true;
       }
     }
 
     $revision_groups = array_select_keys(
       $revision_groups,
       array_keys($revision_order));
 
     $sets = array();
     foreach ($revision_groups as $revision_phid => $group) {
       $revision_ref = head($group)->getRevisionRef();
 
       $set = id(new ArcanistLandCommitSet())
         ->setRevisionRef($revision_ref)
         ->setCommits($group);
 
       $sets[$revision_phid] = $set;
     }
 
     $sets = $this->filterCommitSets($sets);
 
     if (!$this->getShouldPreview()) {
       $this->confirmImplicitCommits($sets, $symbols);
     }
 
     $log->writeStatus(
       pht('LANDING'),
       pht('These changes will land:'));
 
     foreach ($sets as $set) {
       $this->printCommitSet($set);
     }
 
     if ($this->getShouldPreview()) {
       $log->writeStatus(
         pht('PREVIEW'),
         pht('Completed preview of land operation.'));
       return;
     }
 
     $query = pht('Land these changes?');
     $this->getWorkflow()
       ->getPrompt('arc.land.confirm')
       ->setQuery($query)
       ->execute();
 
     $this->confirmRevisions($sets);
 
     $workflow = $this->getWorkflow();
 
     $is_incremental = $this->getIsIncremental();
     $is_hold = $this->getShouldHold();
     $is_keep = $this->getShouldKeep();
 
     $local_state = $api->newLocalState()
       ->setWorkflow($workflow)
       ->saveLocalState();
 
     $this->setLocalState($local_state);
 
     $seen_into = array();
     try {
       $last_key = last_key($sets);
 
       $need_cascade = array();
       $need_prune = array();
 
       foreach ($sets as $set_key => $set) {
         // Add these first, so we don't add them multiple times if we need
         // to retry a push.
         $need_prune[] = $set;
         $need_cascade[] = $set;
 
         while (true) {
           $into_commit = $this->executeMerge($set, $into_commit);
           $this->setHasUnpushedChanges(true);
 
           if ($is_hold) {
             $should_push = false;
           } else if ($is_incremental) {
             $should_push = true;
           } else {
             $is_last = ($set_key === $last_key);
             $should_push = $is_last;
           }
 
           if ($should_push) {
             try {
               $this->pushChange($into_commit);
               $this->setHasUnpushedChanges(false);
             } catch (ArcanistLandPushFailureException $ex) {
 
               // TODO: If the push fails, fetch and retry if the remote ref
               // has moved ahead of us.
 
               if ($this->getIntoLocal()) {
                 $can_retry = false;
               } else if ($this->getIntoEmpty()) {
                 $can_retry = false;
               } else if ($this->getIntoRemote() !== $this->getOntoRemote()) {
                 $can_retry = false;
               } else {
                 $can_retry = false;
               }
 
               if ($can_retry) {
                 // New commit state here
                 $into_commit = '..';
                 continue;
               }
 
               throw new PhutilArgumentUsageException(
                 $ex->getMessage());
             }
 
             if ($need_cascade) {
 
               // NOTE: We cascade each set we've pushed, but we're going to
               // cascade them from most recent to least recent. This way,
               // branches which descend from more recent changes only cascade
               // once, directly in to the correct state.
 
               $need_cascade = array_reverse($need_cascade);
               foreach ($need_cascade as $cascade_set) {
                 $this->cascadeState($set, $into_commit);
               }
               $need_cascade = array();
             }
 
             if (!$is_keep) {
               $this->pruneBranches($need_prune);
               $need_prune = array();
             }
           }
 
           break;
         }
       }
 
       if ($is_hold) {
         $this->didHoldChanges($into_commit);
         $local_state->discardLocalState();
       } else {
         // TODO: Restore this.
         // $this->getWorkflow()->askForRepositoryUpdate();
 
         $this->reconcileLocalState($into_commit, $local_state);
 
         $log->writeSuccess(
           pht('DONE'),
           pht('Landed changes.'));
       }
     } catch (Exception $ex) {
       $local_state->restoreLocalState();
       throw $ex;
     } catch (Throwable $ex) {
       $local_state->restoreLocalState();
       throw $ex;
     }
   }
 
   protected function validateArguments() {
     $log = $this->getLogEngine();
 
     $into_local = $this->getIntoLocalArgument();
     $into_empty = $this->getIntoEmptyArgument();
     $into_remote = $this->getIntoRemoteArgument();
 
     $into_count = 0;
     if ($into_remote !== null) {
       $into_count++;
     }
 
     if ($into_local) {
       $into_count++;
     }
 
     if ($into_empty) {
       $into_count++;
     }
 
     if ($into_count > 1) {
       throw new PhutilArgumentUsageException(
         pht(
           'Arguments "--into-local", "--into-remote", and "--into-empty" '.
           'are mutually exclusive.'));
     }
 
     $into = $this->getIntoArgument();
     if ($into && $into_empty) {
       throw new PhutilArgumentUsageException(
         pht(
           'Arguments "--into" and "--into-empty" are mutually exclusive.'));
     }
 
     $strategy = $this->selectMergeStrategy();
     $this->setStrategy($strategy);
 
     $is_pick = $this->getPickArgument();
     if ($is_pick && !$this->isSquashStrategy()) {
       throw new PhutilArgumentUsageException(
         pht(
           'You can not "--pick" changes under the "merge" strategy.'));
     }
 
     // Build the symbol ref here (which validates the format of the symbol),
     // but don't load the object until later on when we're sure we actually
     // need it, since loading it requires a relatively expensive Conduit call.
     $revision_symbol = $this->getRevisionSymbol();
     if ($revision_symbol) {
       $symbol_ref = id(new ArcanistRevisionSymbolRef())
         ->setSymbol($revision_symbol);
       $this->setRevisionSymbolRef($symbol_ref);
     }
 
     // NOTE: When a user provides: "--hold" or "--preview"; and "--incremental"
     // or various combinations of remote flags, the flags affecting push/remote
     // behavior have no effect.
 
     // These combinations are allowed to support adding "--preview" or "--hold"
     // to any command to run the same command with fewer side effects.
   }
 
   abstract protected function getDefaultSymbols();
   abstract protected function resolveSymbols(array $symbols);
   abstract protected function selectOntoRemote(array $symbols);
   abstract protected function selectOntoRefs(array $symbols);
   abstract protected function confirmOntoRefs(array $onto_refs);
   abstract protected function selectIntoRemote();
   abstract protected function selectIntoRef();
   abstract protected function selectIntoCommit();
   abstract protected function selectCommits($into_commit, array $symbols);
   abstract protected function executeMerge(
     ArcanistLandCommitSet $set,
     $into_commit);
   abstract protected function pushChange($into_commit);
+
+  /**
+   * Update all local refs that depend on refs selected-and-modified during the
+   * land. E.g. with branches named change1 -> change2 -> change3 and using
+   * `arc land change2`, in the general case the local change3 should be
+   * rebased onto the landed version of change2 so that it no longer has
+   * out-of-date ancestors.
+   *
+   * When multiple revisions are landed at once this will be called in a loop
+   * for each set, in order of max to min, where max is the latest descendant
+   * and min is the earliest ancestor. This is done so that non-landing commits
+   * that are descendants of the latest revision will only be rebased once.
+   *
+   * @param ArcanistLandCommitSet  The current commit set to cascade.
+   */
   abstract protected function cascadeState(
     ArcanistLandCommitSet $set,
     $into_commit);
 
   protected function isSquashStrategy() {
     return ($this->getStrategy() === 'squash');
   }
 
+  /**
+   * Prunes the given sets of commits. This should be called after the sets
+   * have been merged.
+   *
+   * @param array  The list of ArcanistLandCommitSet to prune, in order of
+   *   min to max commit set, where min is the earliest ancestor and max
+   *   is the latest descendant.
+   */
   abstract protected function pruneBranches(array $sets);
 
+  /**
+   * Restore the local repository to an expected state after landing. This
+   * should only be called after all changes have been merged, pruned, and
+   * pushed.
+   *
+   * @param string  The commit hash that was landed into.
+   * @param ArcanistRepositoryLocalState  The local state that was captured
+   *   at the beginning of the land process. This may include stashed changes.
+   */
   abstract protected function reconcileLocalState(
     $into_commit,
     ArcanistRepositoryLocalState $state);
 
+  /**
+   * Display information to the user about how to proceed since the land
+   * process was not fully completed. The merged branch has not been pushed.
+   *
+   * @param string  The commit hash that was landed into.
+   */
   abstract protected function didHoldChanges($into_commit);
 
   private function selectMergeStrategy() {
     $log = $this->getLogEngine();
 
     $supported_strategies = array(
       'merge',
       'squash',
     );
     $supported_strategies = array_fuse($supported_strategies);
     $strategy_list = implode(', ', $supported_strategies);
 
     $strategy = $this->getStrategyArgument();
     if ($strategy !== null) {
       if (!isset($supported_strategies[$strategy])) {
         throw new PhutilArgumentUsageException(
           pht(
             'Merge strategy "%s" specified with "--strategy" is unknown. '.
             'Supported merge strategies are: %s.',
             $strategy,
             $strategy_list));
       }
 
       $log->writeStatus(
         pht('STRATEGY'),
         pht(
           'Merging with "%s" strategy, selected with "--strategy".',
           $strategy));
 
       return $strategy;
     }
 
     $strategy = $this->getStrategyFromConfiguration();
     if ($strategy !== null) {
       if (!isset($supported_strategies[$strategy])) {
         throw new PhutilArgumentUsageException(
           pht(
             'Merge strategy "%s" specified in "%s" configuration is '.
             'unknown. Supported merge strategies are: %s.',
             $strategy,
             $this->getStrategyConfigurationKey(),
             $strategy_list));
       }
 
       $log->writeStatus(
         pht('STRATEGY'),
         pht(
           'Merging with "%s" strategy, configured with "%s".',
           $strategy,
           $this->getStrategyConfigurationKey()));
 
       return $strategy;
     }
 
     $strategy = 'squash';
 
     $log->writeStatus(
       pht('STRATEGY'),
       pht(
         'Merging with "%s" strategy, the default strategy.',
         $strategy));
 
     return $strategy;
   }
 
   private function filterCommitSets(array $sets) {
     assert_instances_of($sets, 'ArcanistLandCommitSet');
     $log = $this->getLogEngine();
 
     // If some of the ancestor revisions are already closed, and the user did
     // not specifically indicate that we should land them, and we are using
     // a "squash" strategy, discard those sets.
 
     if ($this->isSquashStrategy()) {
       $discard = array();
       foreach ($sets as $key => $set) {
         $revision_ref = $set->getRevisionRef();
 
         if (!$revision_ref->isClosed()) {
           continue;
         }
 
         if ($set->hasDirectSymbols()) {
           continue;
         }
 
         $discard[] = $set;
         unset($sets[$key]);
       }
 
       if ($discard) {
         echo tsprintf(
           "\n%!\n%W\n",
           pht('DISCARDING ANCESTORS'),
           pht(
             'Some ancestor commits are associated with revisions that have '.
             'already been closed. These changes will be skipped:'));
 
         foreach ($discard as $set) {
           $this->printCommitSet($set);
         }
 
         echo tsprintf("\n");
       }
     }
 
     // TODO: Some of the revisions we've identified may be mapped to an
     // outdated set of commits. We should look in local branches for a better
     // set of commits, and try to confirm that the state we're about to land
     // is the current state in Differential.
 
     $is_pick = $this->getPickArgument();
     if ($is_pick) {
       foreach ($sets as $key => $set) {
         if ($set->hasDirectSymbols()) {
           $set->setIsPick(true);
           continue;
         }
 
         unset($sets[$key]);
       }
     }
 
     return $sets;
   }
 
   final protected function newPassthruCommand($pattern /* , ... */) {
     $workflow = $this->getWorkflow();
     $argv = func_get_args();
 
     $api = $this->getRepositoryAPI();
 
     $passthru = call_user_func_array(
       array($api, 'newPassthru'),
       $argv);
 
     $command = $workflow->newCommand($passthru)
       ->setResolveOnError(true);
 
     return $command;
   }
 
   final protected function newPassthru($pattern /* , ... */) {
     $argv = func_get_args();
 
     $command = call_user_func_array(
       array($this, 'newPassthruCommand'),
       $argv);
 
     return $command->execute();
   }
 
   final protected function getOntoRemoteRef() {
     return id(new ArcanistRemoteRef())
       ->setRemoteName($this->getOntoRemote());
   }
 
 }
diff --git a/src/land/engine/ArcanistMercurialLandEngine.php b/src/land/engine/ArcanistMercurialLandEngine.php
index 6c27abca..030fda97 100644
--- a/src/land/engine/ArcanistMercurialLandEngine.php
+++ b/src/land/engine/ArcanistMercurialLandEngine.php
@@ -1,1165 +1,1275 @@
 <?php
 
 final class ArcanistMercurialLandEngine
   extends ArcanistLandEngine {
 
   private $ontoBranchMarker;
   private $ontoMarkers;
 
+  private $rebasedActiveCommit;
+
   protected function getDefaultSymbols() {
     $api = $this->getRepositoryAPI();
     $log = $this->getLogEngine();
 
     // TODO: In Mercurial, you normally can not create a branch and a bookmark
     // with the same name. However, you can fetch a branch or bookmark from
     // a remote that has the same name as a local branch or bookmark of the
     // other type, and end up with a local branch and bookmark with the same
     // name. We should detect this and treat it as an error.
 
     // TODO: In Mercurial, you can create local bookmarks named
     // "default@default" and similar which do not surive a round trip through
     // a remote. Possibly, we should disallow interacting with these bookmarks.
 
     $markers = $api->newMarkerRefQuery()
       ->withIsActive(true)
       ->execute();
 
     $bookmark = null;
     foreach ($markers as $marker) {
       if ($marker->isBookmark()) {
         $bookmark = $marker->getName();
         break;
       }
     }
 
     if ($bookmark !== null) {
       $log->writeStatus(
         pht('SOURCE'),
         pht(
           'Landing the active bookmark, "%s".',
           $bookmark));
 
       return array($bookmark);
     }
 
     $branch = null;
     foreach ($markers as $marker) {
       if ($marker->isBranch()) {
         $branch = $marker->getName();
         break;
       }
     }
 
     if ($branch !== null) {
       $log->writeStatus(
         pht('SOURCE'),
         pht(
           'Landing the active branch, "%s".',
           $branch));
 
       return array($branch);
     }
 
     $commit = $api->getCanonicalRevisionName('.');
     $commit = $api->getDisplayHash($commit);
 
     $log->writeStatus(
       pht('SOURCE'),
       pht(
         'Landing the active commit, "%s".',
         $api->getDisplayHash($commit)));
 
     return array($commit);
   }
 
   protected function resolveSymbols(array $symbols) {
     assert_instances_of($symbols, 'ArcanistLandSymbol');
     $api = $this->getRepositoryAPI();
 
     $marker_types = array(
       ArcanistMarkerRef::TYPE_BOOKMARK,
       ArcanistMarkerRef::TYPE_BRANCH,
     );
 
     $unresolved = $symbols;
     foreach ($marker_types as $marker_type) {
       $markers = $api->newMarkerRefQuery()
         ->withMarkerTypes(array($marker_type))
         ->execute();
 
       $markers = mgroup($markers, 'getName');
 
       foreach ($unresolved as $key => $symbol) {
         $raw_symbol = $symbol->getSymbol();
 
         $named_markers = idx($markers, $raw_symbol);
         if (!$named_markers) {
           continue;
         }
 
         if (count($named_markers) > 1) {
           echo tsprintf(
             "\n%!\n%W\n\n",
             pht('AMBIGUOUS SYMBOL'),
             pht(
               'Symbol "%s" is ambiguous: it matches multiple markers '.
               '(of type "%s"). Use an unambiguous identifier.',
               $raw_symbol,
               $marker_type));
 
           foreach ($named_markers as $named_marker) {
             echo tsprintf('%s', $named_marker->newRefView());
           }
 
           echo tsprintf("\n");
 
           throw new PhutilArgumentUsageException(
             pht(
               'Symbol "%s" is ambiguous.',
               $raw_symbol));
         }
 
         $marker = head($named_markers);
 
         $symbol->setCommit($marker->getCommitHash());
 
         unset($unresolved[$key]);
       }
     }
 
     foreach ($unresolved as $symbol) {
       $raw_symbol = $symbol->getSymbol();
 
       // TODO: This doesn't have accurate error behavior if the user provides
       // a revset like "x::y".
       try {
         $commit = $api->getCanonicalRevisionName($raw_symbol);
       } catch (CommandException $ex) {
         $commit = null;
       }
 
       if ($commit === null) {
         throw new PhutilArgumentUsageException(
           pht(
             'Symbol "%s" does not identify a bookmark, branch, or commit.',
             $raw_symbol));
       }
 
       $symbol->setCommit($commit);
     }
   }
 
   protected function selectOntoRemote(array $symbols) {
     assert_instances_of($symbols, 'ArcanistLandSymbol');
     $api = $this->getRepositoryAPI();
 
     $remote = $this->newOntoRemote($symbols);
 
     $remote_ref = $api->newRemoteRefQuery()
       ->withNames(array($remote))
       ->executeOne();
     if (!$remote_ref) {
       throw new PhutilArgumentUsageException(
         pht(
           'No remote "%s" exists in this repository.',
           $remote));
     }
 
     // TODO: Allow selection of a bare URI.
 
     return $remote;
   }
 
   private function newOntoRemote(array $symbols) {
     assert_instances_of($symbols, 'ArcanistLandSymbol');
     $api = $this->getRepositoryAPI();
     $log = $this->getLogEngine();
 
     $remote = $this->getOntoRemoteArgument();
     if ($remote !== null) {
 
       $log->writeStatus(
         pht('ONTO REMOTE'),
         pht(
           'Remote "%s" was selected with the "--onto-remote" flag.',
           $remote));
 
       return $remote;
     }
 
     $remote = $this->getOntoRemoteFromConfiguration();
     if ($remote !== null) {
       $remote_key = $this->getOntoRemoteConfigurationKey();
 
       $log->writeStatus(
         pht('ONTO REMOTE'),
         pht(
           'Remote "%s" was selected by reading "%s" configuration.',
           $remote,
           $remote_key));
 
       return $remote;
     }
 
     $api = $this->getRepositoryAPI();
 
     $default_remote = 'default';
 
     $log->writeStatus(
       pht('ONTO REMOTE'),
       pht(
         'Landing onto remote "%s", the default remote under Mercurial.',
         $default_remote));
 
     return $default_remote;
   }
 
   protected function selectOntoRefs(array $symbols) {
     assert_instances_of($symbols, 'ArcanistLandSymbol');
     $log = $this->getLogEngine();
 
     $onto = $this->getOntoArguments();
     if ($onto) {
 
       $log->writeStatus(
         pht('ONTO TARGET'),
         pht(
           'Refs were selected with the "--onto" flag: %s.',
           implode(', ', $onto)));
 
       return $onto;
     }
 
     $onto = $this->getOntoFromConfiguration();
     if ($onto) {
       $onto_key = $this->getOntoConfigurationKey();
 
       $log->writeStatus(
         pht('ONTO TARGET'),
         pht(
           'Refs were selected by reading "%s" configuration: %s.',
           $onto_key,
           implode(', ', $onto)));
 
       return $onto;
     }
 
     $api = $this->getRepositoryAPI();
 
     $default_onto = 'default';
 
     $log->writeStatus(
       pht('ONTO TARGET'),
       pht(
         'Landing onto target "%s", the default target under Mercurial.',
         $default_onto));
 
     return array($default_onto);
   }
 
   protected function confirmOntoRefs(array $onto_refs) {
     $api = $this->getRepositoryAPI();
 
     foreach ($onto_refs as $onto_ref) {
       if (!strlen($onto_ref)) {
         throw new PhutilArgumentUsageException(
           pht(
             'Selected "onto" ref "%s" is invalid: the empty string is not '.
             'a valid ref.',
             $onto_ref));
       }
     }
 
     $remote_ref = $this->getOntoRemoteRef();
 
     $markers = $api->newMarkerRefQuery()
       ->withRemotes(array($remote_ref))
       ->execute();
 
     $onto_markers = array();
     $new_markers = array();
     foreach ($onto_refs as $onto_ref) {
       $matches = array();
       foreach ($markers as $marker) {
         if ($marker->getName() === $onto_ref) {
           $matches[] = $marker;
         }
       }
 
       $match_count = count($matches);
       if ($match_count > 1) {
         throw new PhutilArgumentUsageException(
           pht(
             'TODO: Ambiguous ref.'));
       } else if (!$match_count) {
         $new_bookmark = id(new ArcanistMarkerRef())
           ->setMarkerType(ArcanistMarkerRef::TYPE_BOOKMARK)
           ->setName($onto_ref)
           ->attachRemoteRef($remote_ref);
 
         $onto_markers[] = $new_bookmark;
         $new_markers[] = $new_bookmark;
       } else {
         $onto_markers[] = head($matches);
       }
     }
 
     $branches = array();
     foreach ($onto_markers as $onto_marker) {
       if ($onto_marker->isBranch()) {
         $branches[] = $onto_marker;
       }
 
       $branch_count = count($branches);
       if ($branch_count > 1) {
         echo tsprintf(
           "\n%!\n%W\n\n%W\n\n%W\n\n",
           pht('MULTIPLE "ONTO" BRANCHES'),
           pht(
             'You have selected multiple branches to push changes onto. '.
             'Pushing to multiple branches is not supported by "arc land" '.
             'in Mercurial: Mercurial commits may only belong to one '.
             'branch, so this operation can not be executed atomically.'),
           pht(
             'You may land one branches and any number of bookmarks in a '.
             'single operation.'),
           pht('These branches were selected:'));
 
         foreach ($branches as $branch) {
           echo tsprintf('%s', $branch->newRefView());
         }
 
         echo tsprintf("\n");
 
         throw new PhutilArgumentUsageException(
           pht(
             'Landing onto multiple branches at once is not supported in '.
             'Mercurial.'));
       } else if ($branch_count) {
         $this->ontoBranchMarker = head($branches);
       }
     }
 
     if ($new_markers) {
       echo tsprintf(
         "\n%!\n%W\n\n",
         pht('CREATE %s BOOKMARK(S)', phutil_count($new_markers)),
         pht(
           'These %s symbol(s) do not exist in the remote. They will be '.
           'created as new bookmarks:',
           phutil_count($new_markers)));
 
 
       foreach ($new_markers as $new_marker) {
         echo tsprintf('%s', $new_marker->newRefView());
       }
 
       echo tsprintf("\n");
 
       $is_hold = $this->getShouldHold();
       if ($is_hold) {
         echo tsprintf(
           "%?\n",
           pht(
             'You are using "--hold", so execution will stop before the '.
             '%s bookmark(s) are actually created. You will be given '.
             'instructions to create the bookmarks.',
             phutil_count($new_markers)));
       }
 
       $query = pht(
         'Create %s new remote bookmark(s)?',
         phutil_count($new_markers));
 
       $this->getWorkflow()
         ->getPrompt('arc.land.create')
         ->setQuery($query)
         ->execute();
     }
 
     $this->ontoMarkers = $onto_markers;
   }
 
   protected function selectIntoRemote() {
     $api = $this->getRepositoryAPI();
     $log = $this->getLogEngine();
 
     if ($this->getIntoEmptyArgument()) {
       $this->setIntoEmpty(true);
 
       $log->writeStatus(
         pht('INTO REMOTE'),
         pht(
           'Will merge into empty state, selected with the "--into-empty" '.
           'flag.'));
 
       return;
     }
 
     if ($this->getIntoLocalArgument()) {
       $this->setIntoLocal(true);
 
       $log->writeStatus(
         pht('INTO REMOTE'),
         pht(
           'Will merge into local state, selected with the "--into-local" '.
           'flag.'));
 
       return;
     }
 
     $into = $this->getIntoRemoteArgument();
     if ($into !== null) {
 
       $remote_ref = $api->newRemoteRefQuery()
         ->withNames(array($into))
         ->executeOne();
       if (!$remote_ref) {
         throw new PhutilArgumentUsageException(
           pht(
             'No remote "%s" exists in this repository.',
             $into));
       }
 
       // TODO: Allow a raw URI.
 
       $this->setIntoRemote($into);
 
       $log->writeStatus(
         pht('INTO REMOTE'),
         pht(
           'Will merge into remote "%s", selected with the "--into" flag.',
           $into));
 
       return;
     }
 
     $onto = $this->getOntoRemote();
     $this->setIntoRemote($onto);
 
     $log->writeStatus(
       pht('INTO REMOTE'),
       pht(
         'Will merge into remote "%s" by default, because this is the remote '.
         'the change is landing onto.',
         $onto));
   }
 
   protected function selectIntoRef() {
     $log = $this->getLogEngine();
 
     if ($this->getIntoEmptyArgument()) {
       $log->writeStatus(
         pht('INTO TARGET'),
         pht(
           'Will merge into empty state, selected with the "--into-empty" '.
           'flag.'));
 
       return;
     }
 
     $into = $this->getIntoArgument();
     if ($into !== null) {
       $this->setIntoRef($into);
 
       $log->writeStatus(
         pht('INTO TARGET'),
         pht(
           'Will merge into target "%s", selected with the "--into" flag.',
           $into));
 
       return;
     }
 
     $ontos = $this->getOntoRefs();
     $onto = head($ontos);
 
     $this->setIntoRef($onto);
     if (count($ontos) > 1) {
       $log->writeStatus(
         pht('INTO TARGET'),
         pht(
           'Will merge into target "%s" by default, because this is the first '.
           '"onto" target.',
           $onto));
     } else {
       $log->writeStatus(
         pht('INTO TARGET'),
         pht(
           'Will merge into target "%s" by default, because this is the "onto" '.
           'target.',
           $onto));
     }
   }
 
   protected function selectIntoCommit() {
     $api = $this->getRepositoryAPI();
     $log = $this->getLogEngine();
 
     if ($this->getIntoEmpty()) {
       // If we're running under "--into-empty", we don't have to do anything.
 
       $log->writeStatus(
         pht('INTO COMMIT'),
         pht('Preparing merge into the empty state.'));
 
       return null;
     }
 
     if ($this->getIntoLocal()) {
       // If we're running under "--into-local", just make sure that the
       // target identifies some actual commit.
       $local_ref = $this->getIntoRef();
 
       // TODO: This error handling could probably be cleaner, it will just
       // raise an exception without any context.
 
       $into_commit = $api->getCanonicalRevisionName($local_ref);
 
       $log->writeStatus(
         pht('INTO COMMIT'),
         pht(
           'Preparing merge into local target "%s", at commit "%s".',
           $local_ref,
           $api->getDisplayHash($into_commit)));
 
       return $into_commit;
     }
 
     $target = id(new ArcanistLandTarget())
       ->setRemote($this->getIntoRemote())
       ->setRef($this->getIntoRef());
 
     $commit = $this->fetchTarget($target);
     if ($commit !== null) {
       $log->writeStatus(
         pht('INTO COMMIT'),
         pht(
           'Preparing merge into "%s" from remote "%s", at commit "%s".',
           $target->getRef(),
           $target->getRemote(),
           $api->getDisplayHash($commit)));
       return $commit;
     }
 
     // If we have no valid target and the user passed "--into" explicitly,
     // treat this as an error. For example, "arc land --into Q --onto Q",
     // where "Q" does not exist, is an error.
     if ($this->getIntoArgument()) {
       throw new PhutilArgumentUsageException(
         pht(
           'Ref "%s" does not exist in remote "%s".',
           $target->getRef(),
           $target->getRemote()));
     }
 
     // Otherwise, treat this as implying "--into-empty". For example,
     // "arc land --onto Q", where "Q" does not exist, is equivalent to
     // "arc land --into-empty --onto Q".
     $this->setIntoEmpty(true);
 
     $log->writeStatus(
       pht('INTO COMMIT'),
       pht(
         'Preparing merge into the empty state to create target "%s" '.
         'in remote "%s".',
         $target->getRef(),
         $target->getRemote()));
 
     return null;
   }
 
   private function fetchTarget(ArcanistLandTarget $target) {
     $api = $this->getRepositoryAPI();
     $log = $this->getLogEngine();
 
     $target_name = $target->getRef();
 
     $remote_ref = id(new ArcanistRemoteRef())
       ->setRemoteName($target->getRemote());
 
     $markers = $api->newMarkerRefQuery()
       ->withRemotes(array($remote_ref))
       ->withNames(array($target_name))
       ->execute();
 
     $bookmarks = array();
     $branches = array();
     foreach ($markers as $marker) {
       if ($marker->isBookmark()) {
         $bookmarks[] = $marker;
       } else {
         $branches[] = $marker;
       }
     }
 
     if (!$bookmarks && !$branches) {
       throw new PhutilArgumentUsageException(
         pht(
           'Remote "%s" has no bookmark or branch named "%s".',
           $target->getRemote(),
           $target->getRef()));
     }
 
     if ($bookmarks && $branches) {
       echo tsprintf(
         "\n%!\n%W\n\n",
         pht('AMBIGUOUS MARKER'),
         pht(
           'In remote "%s", the name "%s" identifies one or more branch '.
           'heads and one or more bookmarks. Close, rename, or delete all '.
           'but one of these markers, or pull the state you want to merge '.
           'into and use "--into-local --into <hash>" to disambiguate the '.
           'desired merge target.',
           $target->getRemote(),
           $target->getRef()));
 
       throw new PhutilArgumentUsageException(
         pht('Merge target is ambiguous.'));
     }
 
     if ($bookmarks) {
       if (count($bookmarks) > 1) {
         throw new Exception(
           pht(
             'Remote "%s" has multiple bookmarks with name "%s". This '.
             'is unexpected.',
             $target->getRemote(),
             $target->getRef()));
       }
       $bookmark = head($bookmarks);
 
       $target_marker = $bookmark;
     }
 
     if ($branches) {
       if (count($branches) > 1) {
         echo tsprintf(
           "\n%!\n%W\n\n",
           pht('MULTIPLE BRANCH HEADS'),
           pht(
             'Remote "%s" has multiple branch heads named "%s". Close all '.
             'but one, or pull the head you want and use "--into-local '.
             '--into <hash>" to specify an explicit merge target.',
             $target->getRemote(),
             $target->getRef()));
 
         throw new PhutilArgumentUsageException(
           pht(
             'Remote branch has multiple heads.'));
       }
 
       $branch = head($branches);
 
       $target_marker = $branch;
     }
 
     if ($target_marker->isBranch()) {
       $err = $this->newPassthru(
         'pull --branch %s -- %s',
         $target->getRef(),
         $target->getRemote());
     } else {
 
       // NOTE: This may have side effects:
       //
       //   - It can create a "bookmark@remote" bookmark if there is a local
       //     bookmark with the same name that is not an ancestor.
       //   - It can create an arbitrary number of other bookmarks.
       //
       // Since these seem to generally be intentional behaviors in Mercurial,
       // and should theoretically be familiar to Mercurial users, just accept
       // them as the cost of doing business.
 
       $err = $this->newPassthru(
         'pull --bookmark %s -- %s',
         $target->getRef(),
         $target->getRemote());
     }
 
     // NOTE: It's possible that between the time we ran "ls-markers" and the
     // time we ran "pull" that the remote changed.
 
     // It may even have been rewound or rewritten, in which case we did not
     // actually fetch the ref we are about to return as a target. For now,
     // assume this didn't happen: it's so unlikely that it's probably not
     // worth spending 100ms to check.
 
     // TODO: If the Mercurial command server is revived, this check becomes
     // more reasonable if it's cheap.
 
     return $target_marker->getCommitHash();
   }
 
   protected function selectCommits($into_commit, array $symbols) {
     assert_instances_of($symbols, 'ArcanistLandSymbol');
     $api = $this->getRepositoryAPI();
 
     $commit_map = array();
     foreach ($symbols as $symbol) {
       $symbol_commit = $symbol->getCommit();
-      $template = '{node}-{parents}-';
-
+      $template = '{node}-{parents % \'{node} \'}-{desc|firstline}\\n';
+
+      // The returned array of commits is expected to be ordered by max to min
+      // where the max commit has no descendants in the range and the min
+      // commit has no ancestors in the range. Use 'reverse()' in the template
+      // so the output is ordered with the max commit as the first line. The
+      // max/min terms are used in a topological sense as chronological terms
+      // for commits may be misleading or incorrect in some situations.
       if ($into_commit === null) {
         list($commits) = $api->execxLocal(
           'log --rev %s --template %s --',
           hgsprintf('reverse(ancestors(%s))', $into_commit),
           $template);
       } else {
         list($commits) = $api->execxLocal(
           'log --rev %s --template %s --',
           hgsprintf(
             'reverse(ancestors(%s) - ancestors(%s))',
             $symbol_commit,
             $into_commit),
           $template);
       }
 
       $commits = phutil_split_lines($commits, false);
       $is_first = true;
       foreach ($commits as $line) {
         if (!strlen($line)) {
           continue;
         }
 
         $parts = explode('-', $line, 3);
         if (count($parts) < 3) {
           throw new Exception(
             pht(
               'Unexpected output from "hg log ...": %s',
               $line));
         }
 
         $hash = $parts[0];
         if (!isset($commit_map[$hash])) {
           $parents = $parts[1];
           $parents = trim($parents);
           if (strlen($parents)) {
             $parents = explode(' ', $parents);
           } else {
             $parents = array();
           }
 
           $summary = $parts[2];
 
           $commit_map[$hash] = id(new ArcanistLandCommit())
             ->setHash($hash)
             ->setParents($parents)
             ->setSummary($summary);
         }
 
         $commit = $commit_map[$hash];
         if ($is_first) {
           $commit->addDirectSymbol($symbol);
           $is_first = false;
         }
 
         $commit->addIndirectSymbol($symbol);
       }
     }
 
     return $this->confirmCommits($into_commit, $symbols, $commit_map);
   }
 
   protected function executeMerge(ArcanistLandCommitSet $set, $into_commit) {
     $api = $this->getRepositoryAPI();
 
     if ($this->getStrategy() !== 'squash') {
       throw new Exception(pht('TODO: Support merge strategies'));
     }
 
     // See PHI1808. When we "hg rebase ..." below, Mercurial will move
     // bookmarks which point at the old commit range to point at the rebased
     // commit. This is somewhat surprising and we don't want this to happen:
     // save the old bookmark state so we can put the bookmarks back before
     // we continue.
 
     $bookmark_refs = $api->newMarkerRefQuery()
       ->withMarkerTypes(
         array(
           ArcanistMarkerRef::TYPE_BOOKMARK,
         ))
       ->execute();
 
     // TODO: Add a Mercurial version check requiring 2.1.1 or newer.
 
     $api->execxLocal(
       'update --rev %s',
       hgsprintf('%s', $into_commit));
 
     $commits = $set->getCommits();
 
-    $min_commit = last($commits)->getHash();
-    $max_commit = head($commits)->getHash();
+    // confirmCommits() reverses the order of the commits as they're ordered
+    // above in selectCommits(). Now the head of the list is the min commit and
+    // the last is the max commit, where within the range the max commit has no
+    // descendants and the min commit has no ancestors. The min/max terms are
+    // used in a topological sense as chronological terms for commits can be
+    // misleading or incorrect in certain situations.
+    $max_commit = last($commits)->getHash();
+    $min_commit = head($commits)->getHash();
 
     $revision_ref = $set->getRevisionRef();
     $commit_message = $revision_ref->getCommitMessage();
 
     // If we're landing "--onto" a branch, set that as the branch marker
     // before creating the new commit.
 
     // TODO: We could skip this if we know that the "$into_commit" already
     // has the right branch, which it will if we created it.
 
     $branch_marker = $this->ontoBranchMarker;
     if ($branch_marker) {
       $api->execxLocal('branch -- %s', $branch_marker->getName());
     }
 
     try {
       $argv = array();
       $argv[] = '--dest';
       $argv[] = hgsprintf('%s', $into_commit);
 
       $argv[] = '--rev';
       $argv[] = hgsprintf('%s..%s', $min_commit, $max_commit);
 
       $argv[] = '--logfile';
       $argv[] = '-';
 
       $argv[] = '--keep';
       $argv[] = '--collapse';
 
       $future = $api->execFutureLocal('rebase %Ls', $argv);
       $future->write($commit_message);
       $future->resolvex();
 
     } catch (CommandException $ex) {
-      // TODO
-      // $api->execManualLocal('rebase --abort');
+      // Aborting the rebase should restore the same state prior to running the
+      // rebase command.
+      $api->execManualLocal('rebase --abort');
       throw $ex;
     }
 
     // Find all the bookmarks which pointed at commits we just rebased, and
     // put them back the way they were before rebasing moved them. We aren't
     // deleting the old commits yet and don't want to move the bookmarks.
 
     $obsolete_map = array();
     foreach ($set->getCommits() as $commit) {
       $obsolete_map[$commit->getHash()] = true;
     }
 
     foreach ($bookmark_refs as $bookmark_ref) {
       $bookmark_hash = $bookmark_ref->getCommitHash();
 
       if (!isset($obsolete_map[$bookmark_hash])) {
         continue;
       }
 
       $api->execxLocal(
         'bookmark --force --rev %s -- %s',
         $bookmark_hash,
         $bookmark_ref->getName());
     }
 
     list($stdout) = $api->execxLocal('log --rev tip --template %s', '{node}');
     $new_cursor = trim($stdout);
 
+    // If any of the commits that were rebased was the active commit before the
+    // workflow started, track the new commit so it can be used as the working
+    // directory after the land has succeeded.
+    if (isset($obsolete_map[$this->getLocalState()->getLocalCommit()])) {
+      $this->rebasedActiveCommit = $new_cursor;
+    }
+
     return $new_cursor;
   }
 
   protected function pushChange($into_commit) {
     $api = $this->getRepositoryAPI();
 
-    list($head, $body, $tail) = $this->newPushCommands($into_commit);
+    list($head, $body, $tail_pass, $tail_fail) = $this->newPushCommands(
+      $into_commit);
 
     foreach ($head as $command) {
       $api->execxLocal('%Ls', $command);
     }
 
     try {
       foreach ($body as $command) {
         $err = $this->newPassthru('%Ls', $command);
         if ($err) {
           throw new ArcanistLandPushFailureException(
             pht(
               'Push failed! Fix the error and run "arc land" again.'));
         }
       }
-    } finally {
-      foreach ($tail as $command) {
+
+      foreach ($tail_pass as $command) {
+        $api->execxLocal('%Ls', $command);
+      }
+    } catch (Exception $ex) {
+      foreach ($tail_fail as $command) {
+        $api->execxLocal('%Ls', $command);
+      }
+      throw $ex;
+    } catch (Throwable $ex) {
+      foreach ($tail_fail as $command) {
         $api->execxLocal('%Ls', $command);
       }
+      throw $ex;
     }
   }
 
   private function newPushCommands($into_commit) {
     $api = $this->getRepositoryAPI();
 
     $head_commands = array();
     $body_commands = array();
-    $tail_commands = array();
+    $tail_pass_commands = array();
+    $tail_fail_commands = array();
 
     $bookmarks = array();
     foreach ($this->ontoMarkers as $onto_marker) {
       if (!$onto_marker->isBookmark()) {
         continue;
       }
       $bookmarks[] = $onto_marker;
     }
 
     // If we're pushing to bookmarks, move all the bookmarks we want to push
     // to the merge commit. (There doesn't seem to be any way to specify
     // "push commit X as bookmark Y" in Mercurial.)
 
-    $restore = array();
+    $restore_bookmarks = array();
     if ($bookmarks) {
       $markers = $api->newMarkerRefQuery()
         ->withNames(mpull($bookmarks, 'getName'))
         ->withMarkerTypes(array(ArcanistMarkerRef::TYPE_BOOKMARK))
         ->execute();
       $markers = mpull($markers, 'getCommitHash', 'getName');
 
       foreach ($bookmarks as $bookmark) {
         $bookmark_name = $bookmark->getName();
 
         $old_position = idx($markers, $bookmark_name);
         $new_position = $into_commit;
 
         if ($old_position === $new_position) {
           continue;
         }
 
         $head_commands[] = array(
           'bookmark',
           '--force',
           '--rev',
           hgsprintf('%s', $api->getDisplayHash($new_position)),
           '--',
           $bookmark_name,
         );
 
         $api->execxLocal(
           'bookmark --force --rev %s -- %s',
           hgsprintf('%s', $new_position),
           $bookmark_name);
 
-        $restore[$bookmark_name] = $old_position;
+        if ($old_position !== null) {
+          $restore_bookmarks[$bookmark_name] = $old_position;
+        }
       }
     }
 
     // Now, prepare the actual push.
 
     $argv = array();
     $argv[] = 'push';
 
     if ($bookmarks) {
       // If we're pushing at least one bookmark, we can just specify the list
       // of bookmarks as things we want to push.
       foreach ($bookmarks as $bookmark) {
         $argv[] = '--bookmark';
         $argv[] = $bookmark->getName();
       }
     } else {
       // Otherwise, specify the commit itself.
       $argv[] = '--rev';
       $argv[] = hgsprintf('%s', $into_commit);
     }
 
     $argv[] = '--';
     $argv[] = $this->getOntoRemote();
 
     $body_commands[] = $argv;
 
     // Finally, restore the bookmarks.
 
-    foreach ($restore as $bookmark_name => $old_position) {
-      $tail = array();
-      $tail[] = 'bookmark';
-
-      if ($old_position === null) {
-        $tail[] = '--delete';
-      } else {
-        $tail[] = '--force';
-        $tail[] = '--rev';
-        $tail[] = hgsprintf('%s', $api->getDisplayHash($old_position));
+    if ($restore_bookmarks) {
+      // Instead of restoring the previous state, assume landing onto bookmarks
+      // also updates those bookmarks in the remote. After pushing, pull the
+      // latest state of these bookmarks. Mercurial allows pulling multiple
+      // bookmarks in a single pull command which will be faster than pulling
+      // them from a remote individually.
+      $tail = array(
+        'pull',
+      );
+
+      foreach ($restore_bookmarks as $bookmark_name => $old_position) {
+        $tail[] = '--bookmark';
+        $tail[] = $bookmark_name;
+
+        // In the failure case restore the state of the bookmark. Mercurial
+        // does not provide a way to move multiple bookmarks in a single
+        // command however these commands do not involve the remote.
+        $tail_fail_commands[] = array(
+          'bookmark',
+          '--force',
+          '--rev',
+          hgsprintf('%s', $api->getDisplayHash($old_position)),
+        );
       }
 
-      $tail[] = '--';
-      $tail[] = $bookmark_name;
-
-      $tail_commands[] = $tail;
+      if ($tail) {
+        $tail_pass_commands[] = $tail;
+      }
     }
 
     return array(
       $head_commands,
       $body_commands,
-      $tail_commands,
+      $tail_pass_commands,
+      $tail_fail_commands,
     );
   }
 
   protected function cascadeState(ArcanistLandCommitSet $set, $into_commit) {
     $api = $this->getRepositoryAPI();
     $log = $this->getLogEngine();
 
     // This has no effect when we're executing a merge strategy.
     if (!$this->isSquashStrategy()) {
       return;
     }
 
     $old_commit = last($set->getCommits())->getHash();
     $new_commit = $into_commit;
 
     list($output) = $api->execxLocal(
       'log --rev %s --template %s',
       hgsprintf('children(%s)', $old_commit),
       '{node}\n');
     $child_hashes = phutil_split_lines($output, false);
 
     foreach ($child_hashes as $child_hash) {
       if (!strlen($child_hash)) {
         continue;
       }
 
       // TODO: If the only heads which are descendants of this child will
       // be deleted, we can skip this rebase?
 
       try {
         $api->execxLocal(
           'rebase --source %s --dest %s --keep --keepbranches',
           $child_hash,
           $new_commit);
       } catch (CommandException $ex) {
-        // TODO: Recover state.
+        // Aborting the rebase should restore the same state prior to running
+        // the rebase command.
+        $api->execManualLocal('rebase --abort');
         throw $ex;
       }
     }
   }
 
 
   protected function pruneBranches(array $sets) {
     assert_instances_of($sets, 'ArcanistLandCommitSet');
     $api = $this->getRepositoryAPI();
     $log = $this->getLogEngine();
 
     // This has no effect when we're executing a merge strategy.
     if (!$this->isSquashStrategy()) {
       return;
     }
 
     $revs = array();
     $obsolete_map = array();
 
+    $using_evolve = $api->getMercurialFeature('evolve');
+
     // We've rebased all descendants already, so we can safely delete all
     // of these commits.
 
     $sets = array_reverse($sets);
     foreach ($sets as $set) {
       $commits = $set->getCommits();
 
+      // In the commit set the min commit should be the commit with no
+      // ancestors and the max commit should be the commit with no descendants.
+      // The min/max terms are used in a toplogical sense as chronological
+      // terms for commits may be misleading or incorrect in some situations.
       $min_commit = head($commits)->getHash();
       $max_commit = last($commits)->getHash();
 
-      $revs[] = hgsprintf('%s::%s', $min_commit, $max_commit);
+      if ($using_evolve) {
+        // If non-head series of commits are rebased while the evolve extension
+        // is in use, the rebase leaves behind the entire series of descendants
+        // in which case the entire chain needs removed, not just a section.
+        // Otherwise this results in the prune leaving behind orphaned commits.
+        $revs[] = hgsprintf('%s::', $min_commit);
+      } else {
+        $revs[] = hgsprintf('%s::%s', $min_commit, $max_commit);
+      }
 
       foreach ($commits as $commit) {
         $obsolete_map[$commit->getHash()] = true;
       }
     }
 
     $rev_set = '('.implode(') or (', $revs).')';
 
     // See PHI45. If we have "hg evolve", get rid of old commits using
     // "hg prune" instead of "hg strip".
 
     // If we "hg strip" a commit which has an obsolete predecessor, it
     // removes the obsolescence marker and revives the predecessor. This is
     // not desirable: we want to destroy all predecessors of these commits.
 
     // See PHI1808. Both "hg strip" and "hg prune" move bookmarks backwards in
     // history rather than destroying them. Instead, we want to destroy any
     // bookmarks which point at these now-obsoleted commits.
 
     $bookmark_refs = $api->newMarkerRefQuery()
-      ->withMarkerTypes(
-        array(
-          ArcanistMarkerRef::TYPE_BOOKMARK,
-        ))
+      ->withMarkerTypes(array(ArcanistMarkerRef::TYPE_BOOKMARK))
       ->execute();
     foreach ($bookmark_refs as $bookmark_ref) {
       $bookmark_hash = $bookmark_ref->getCommitHash();
       $bookmark_name = $bookmark_ref->getName();
 
       if (!isset($obsolete_map[$bookmark_hash])) {
         continue;
       }
 
       $log->writeStatus(
         pht('CLEANUP'),
         pht('Deleting bookmark "%s".', $bookmark_name));
 
       $api->execxLocal(
         'bookmark --delete -- %s',
         $bookmark_name);
     }
 
-    if ($api->getMercurialFeature('evolve')) {
+    if ($using_evolve) {
       $api->execxLocal(
         'prune --rev %s',
         $rev_set);
     } else {
       $api->execxLocal(
         '--config extensions.strip= strip --rev %s',
         $rev_set);
     }
   }
 
   protected function reconcileLocalState(
     $into_commit,
     ArcanistRepositoryLocalState $state) {
 
-    // TODO: For now, just leave users wherever they ended up.
+    $api = $this->getRepositoryAPI();
+
+    // If the starting working state was not part of land process just update
+    // to that original working state.
+    if ($this->rebasedActiveCommit === null) {
+      $update_marker = $this->getLocalState()->getLocalCommit();
+      if ($this->getLocalState()->getLocalBookmark() !== null) {
+        $update_marker = $this->getLocalState()->getLocalBookmark();
+      }
+
+      $api->execxLocal(
+        'update -- %s',
+        $update_marker);
+
+      $state->discardLocalState();
+      return;
+    }
+
+    // If the working state was landed into multiple destinations then the
+    // resulting working state is ambiguous.
+    if (count($this->ontoMarkers) != 1) {
+      $state->discardLocalState();
+      return;
+    }
+
+    // Get the current state of bookmarks
+    $bookmark_refs = $api->newMarkerRefQuery()
+      ->withMarkerTypes(array(ArcanistMarkerRef::TYPE_BOOKMARK))
+      ->execute();
+
+    $update_marker = $this->rebasedActiveCommit;
+
+    // Find any bookmarks which exist on the commit which is the result of the
+    // starting working directory's rebase. If any of those bookmarks are also
+    // the destination marker then we use that bookmark as the update in order
+    // for it to become active.
+    $onto_marker = $this->ontoMarkers[0]->getName();
+    foreach ($bookmark_refs as $bookmark_ref) {
+      if ($bookmark_ref->getCommitHash() == $this->rebasedActiveCommit &&
+        $bookmark_ref->getName() == $onto_marker) {
+          $update_marker = $onto_marker;
+          break;
+      }
+    }
+
+    $api->execxLocal(
+      'update -- %s',
+      $update_marker);
 
     $state->discardLocalState();
   }
 
   protected function didHoldChanges($into_commit) {
     $log = $this->getLogEngine();
     $local_state = $this->getLocalState();
 
     $message = pht(
       'Holding changes locally, they have not been pushed.');
 
-    list($head, $body, $tail) = $this->newPushCommands($into_commit);
-    $commands = array_merge($head, $body, $tail);
+    list($head, $body, $tail_pass, $tail_fail) = $this->newPushCommands(
+      $into_commit);
+    $commands = array_merge($head, $body, $tail_pass);
 
     echo tsprintf(
       "\n%!\n%s\n\n",
       pht('HOLD CHANGES'),
       $message);
 
     echo tsprintf(
       "%s\n\n",
       pht('To push changes manually, run these %s command(s):',
         phutil_count($commands)));
 
     foreach ($commands as $command) {
       echo tsprintf('%>', csprintf('hg %Ls', $command));
     }
 
     echo tsprintf("\n");
 
     $restore_commands = $local_state->getRestoreCommandsForDisplay();
     if ($restore_commands) {
       echo tsprintf(
         "%s\n\n",
         pht(
           'To go back to how things were before you ran "arc land", run '.
           'these %s command(s):',
           phutil_count($restore_commands)));
 
       foreach ($restore_commands as $restore_command) {
         echo tsprintf('%>', $restore_command);
       }
 
       echo tsprintf("\n");
     }
 
     echo tsprintf(
       "%s\n",
       pht(
         'Local branches and bookmarks have not been changed, and are still '.
         'in the same state as before.'));
   }
 
 }
diff --git a/src/repository/state/ArcanistMercurialLocalState.php b/src/repository/state/ArcanistMercurialLocalState.php
index fd551547..dae4127e 100644
--- a/src/repository/state/ArcanistMercurialLocalState.php
+++ b/src/repository/state/ArcanistMercurialLocalState.php
@@ -1,187 +1,195 @@
 <?php
 
 final class ArcanistMercurialLocalState
   extends ArcanistRepositoryLocalState {
 
   private $localCommit;
   private $localBranch;
   private $localBookmark;
 
+  public function getLocalCommit() {
+    return $this->localCommit;
+  }
+
+  public function getLocalBookmark() {
+    return $this->localBookmark;
+  }
+
   protected function executeSaveLocalState() {
     $api = $this->getRepositoryAPI();
     $log = $this->getWorkflow()->getLogEngine();
 
     $markers = $api->newMarkerRefQuery()
       ->execute();
 
     $local_commit = null;
     foreach ($markers as $marker) {
       if ($marker->isCommitState()) {
         $local_commit = $marker->getCommitHash();
       }
     }
 
     if ($local_commit === null) {
       throw new Exception(
         pht(
           'Unable to identify the current commit in the working copy.'));
     }
 
     $this->localCommit = $local_commit;
 
     $local_branch = null;
     foreach ($markers as $marker) {
       if ($marker->isBranchState()) {
         $local_branch = $marker->getName();
         break;
       }
     }
 
     if ($local_branch === null) {
       throw new Exception(
         pht(
           'Unable to identify the current branch in the working copy.'));
     }
 
     if ($local_branch !== null) {
       $this->localBranch = $local_branch;
     }
 
     $local_bookmark = null;
     foreach ($markers as $marker) {
       if ($marker->isBookmark()) {
         if ($marker->getIsActive()) {
           $local_bookmark = $marker->getName();
           break;
         }
       }
     }
 
     if ($local_bookmark !== null) {
       $this->localBookmark = $local_bookmark;
     }
 
     $has_bookmark = ($this->localBookmark !== null);
 
     if ($has_bookmark) {
       $location = pht(
         'Saving local state (at "%s" on branch "%s", bookmarked as "%s").',
         $api->getDisplayHash($this->localCommit),
         $this->localBranch,
         $this->localBookmark);
     } else {
       $location = pht(
         'Saving local state (at "%s" on branch "%s").',
         $api->getDisplayHash($this->localCommit),
         $this->localBranch);
     }
 
     $log->writeTrace(pht('SAVE STATE'), $location);
   }
 
   protected function executeRestoreLocalState() {
     $api = $this->getRepositoryAPI();
     $log = $this->getWorkflow()->getLogEngine();
 
     if ($this->localBookmark !== null) {
       $location = pht(
         'Restoring local state (at "%s" on branch "%s", bookmarked as "%s").',
         $api->getDisplayHash($this->localCommit),
         $this->localBranch,
         $this->localBookmark);
     } else {
       $location = pht(
         'Restoring local state (at "%s" on branch "%s").',
         $api->getDisplayHash($this->localCommit),
         $this->localBranch);
     }
 
     $log->writeStatus(pht('LOAD STATE'), $location);
 
     $api->execxLocal('update -- %s', $this->localCommit);
     $api->execxLocal('branch --force -- %s', $this->localBranch);
 
     if ($this->localBookmark !== null) {
       $api->execxLocal('bookmark --force -- %s', $this->localBookmark);
     }
   }
 
   protected function executeDiscardLocalState() {
     return;
   }
 
   protected function canStashChanges() {
     $api = $this->getRepositoryAPI();
     return $api->getMercurialFeature('shelve');
   }
 
   protected function getIgnoreHints() {
     return array(
       pht(
         'To configure Mercurial to ignore certain files in the working '.
         'copy, add them to ".hgignore".'),
     );
   }
 
   protected function newRestoreCommandsForDisplay() {
     $api = $this->getRepositoryAPI();
     $commands = array();
 
     $commands[] = csprintf(
       'hg update -- %s',
       $api->getDisplayHash($this->localCommit));
 
     $commands[] = csprintf(
       'hg branch --force -- %s',
       $this->localBranch);
 
     if ($this->localBookmark !== null) {
       $commands[] = csprintf(
         'hg bookmark --force -- %s',
         $this->localBookmark);
     }
 
     return $commands;
   }
 
   protected function saveStash() {
     $api = $this->getRepositoryAPI();
     $log = $this->getWorkflow()->getLogEngine();
 
     $stash_ref = sprintf(
       'arc-%s',
       Filesystem::readRandomCharacters(12));
 
     $api->execxLocal(
       '--config extensions.shelve= shelve --unknown --name %s --',
       $stash_ref);
 
     $log->writeStatus(
       pht('SHELVE'),
       pht('Shelving uncommitted changes from working copy.'));
 
     return $stash_ref;
   }
 
   protected function restoreStash($stash_ref) {
     $api = $this->getRepositoryAPI();
     $log = $this->getWorkflow()->getLogEngine();
 
     $log->writeStatus(
       pht('UNSHELVE'),
       pht('Restoring uncommitted changes to working copy.'));
 
     $api->execxLocal(
       '--config extensions.shelve= unshelve --keep --name %s --',
       $stash_ref);
   }
 
   protected function discardStash($stash_ref) {
     $api = $this->getRepositoryAPI();
 
     $api->execxLocal(
       '--config extensions.shelve= shelve --delete %s --',
       $stash_ref);
   }
 
 }