diff --git a/src/applications/project/editor/PhabricatorProjectTransactionEditor.php b/src/applications/project/editor/PhabricatorProjectTransactionEditor.php
index 729674e120..eb57c39b2c 100644
--- a/src/applications/project/editor/PhabricatorProjectTransactionEditor.php
+++ b/src/applications/project/editor/PhabricatorProjectTransactionEditor.php
@@ -1,438 +1,457 @@
 <?php
 
 final class PhabricatorProjectTransactionEditor
   extends PhabricatorApplicationTransactionEditor {
 
   private $isMilestone;
 
   private function setIsMilestone($is_milestone) {
     $this->isMilestone = $is_milestone;
     return $this;
   }
 
   public function getIsMilestone() {
     return $this->isMilestone;
   }
 
   public function getEditorApplicationClass() {
     return 'PhabricatorProjectApplication';
   }
 
   public function getEditorObjectsDescription() {
     return pht('Projects');
   }
 
   public function getCreateObjectTitle($author, $object) {
     return pht('%s created this project.', $author);
   }
 
   public function getCreateObjectTitleForFeed($author, $object) {
     return pht('%s created %s.', $author, $object);
   }
 
   public function getTransactionTypes() {
     $types = parent::getTransactionTypes();
 
     $types[] = PhabricatorTransactions::TYPE_EDGE;
     $types[] = PhabricatorTransactions::TYPE_VIEW_POLICY;
     $types[] = PhabricatorTransactions::TYPE_EDIT_POLICY;
     $types[] = PhabricatorTransactions::TYPE_JOIN_POLICY;
 
     return $types;
   }
 
   protected function validateAllTransactions(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $errors = array();
 
     // Prevent creating projects which are both subprojects and milestones,
     // since this does not make sense, won't work, and will break everything.
     $parent_xaction = null;
     foreach ($xactions as $xaction) {
       switch ($xaction->getTransactionType()) {
         case PhabricatorProjectParentTransaction::TRANSACTIONTYPE:
         case PhabricatorProjectMilestoneTransaction::TRANSACTIONTYPE:
           if ($xaction->getNewValue() === null) {
             continue 2;
           }
 
           if (!$parent_xaction) {
             $parent_xaction = $xaction;
             continue 2;
           }
 
           $errors[] = new PhabricatorApplicationTransactionValidationError(
             $xaction->getTransactionType(),
             pht('Invalid'),
             pht(
               'When creating a project, specify a maximum of one parent '.
               'project or milestone project. A project can not be both a '.
               'subproject and a milestone.'),
             $xaction);
           break 2;
       }
     }
 
     $is_milestone = $this->getIsMilestone();
 
     $is_parent = $object->getHasSubprojects();
 
     foreach ($xactions as $xaction) {
       switch ($xaction->getTransactionType()) {
         case PhabricatorTransactions::TYPE_EDGE:
           $type = $xaction->getMetadataValue('edge:type');
           if ($type != PhabricatorProjectProjectHasMemberEdgeType::EDGECONST) {
             break;
           }
 
           if ($is_parent) {
             $errors[] = new PhabricatorApplicationTransactionValidationError(
               $xaction->getTransactionType(),
               pht('Invalid'),
               pht(
                 'You can not change members of a project with subprojects '.
                 'directly. Members of any subproject are automatically '.
                 'members of the parent project.'),
               $xaction);
           }
 
           if ($is_milestone) {
             $errors[] = new PhabricatorApplicationTransactionValidationError(
               $xaction->getTransactionType(),
               pht('Invalid'),
               pht(
                 'You can not change members of a milestone. Members of the '.
                 'parent project are automatically members of the milestone.'),
               $xaction);
           }
           break;
       }
     }
 
     return $errors;
   }
 
   protected function willPublish(PhabricatorLiskDAO $object, array $xactions) {
     // NOTE: We're using the omnipotent user here because the original actor
     // may no longer have permission to view the object.
     return id(new PhabricatorProjectQuery())
       ->setViewer(PhabricatorUser::getOmnipotentUser())
       ->withPHIDs(array($object->getPHID()))
       ->needAncestorMembers(true)
       ->executeOne();
   }
 
   protected function shouldSendMail(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return true;
   }
 
   protected function getMailSubjectPrefix() {
     return pht('[Project]');
   }
 
   protected function getMailTo(PhabricatorLiskDAO $object) {
     return array(
       $this->getActingAsPHID(),
     );
   }
 
   protected function getMailCc(PhabricatorLiskDAO $object) {
     return array();
   }
 
   public function getMailTagsMap() {
     return array(
       PhabricatorProjectTransaction::MAILTAG_METADATA =>
         pht('Project name, hashtags, icon, image, or color changes.'),
       PhabricatorProjectTransaction::MAILTAG_MEMBERS =>
         pht('Project membership changes.'),
       PhabricatorProjectTransaction::MAILTAG_WATCHERS =>
         pht('Project watcher list changes.'),
       PhabricatorProjectTransaction::MAILTAG_OTHER =>
         pht('Other project activity not listed above occurs.'),
     );
   }
 
   protected function buildReplyHandler(PhabricatorLiskDAO $object) {
     return id(new ProjectReplyHandler())
       ->setMailReceiver($object);
   }
 
   protected function buildMailTemplate(PhabricatorLiskDAO $object) {
     $name = $object->getName();
 
     return id(new PhabricatorMetaMTAMail())
       ->setSubject("{$name}");
   }
 
   protected function buildMailBody(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $body = parent::buildMailBody($object, $xactions);
 
     $uri = '/project/profile/'.$object->getID().'/';
     $body->addLinkSection(
       pht('PROJECT DETAIL'),
       PhabricatorEnv::getProductionURI($uri));
 
     return $body;
   }
 
   protected function shouldPublishFeedStory(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return true;
   }
 
   protected function supportsSearch() {
     return true;
   }
 
   protected function applyFinalEffects(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $materialize = false;
     $new_parent = null;
     foreach ($xactions as $xaction) {
       switch ($xaction->getTransactionType()) {
         case PhabricatorTransactions::TYPE_EDGE:
           switch ($xaction->getMetadataValue('edge:type')) {
             case PhabricatorProjectProjectHasMemberEdgeType::EDGECONST:
               $materialize = true;
               break;
           }
           break;
         case PhabricatorProjectParentTransaction::TRANSACTIONTYPE:
         case PhabricatorProjectMilestoneTransaction::TRANSACTIONTYPE:
           $materialize = true;
           $new_parent = $object->getParentProject();
           break;
       }
     }
 
     if ($new_parent) {
       // If we just created the first subproject of this parent, we want to
       // copy all of the real members to the subproject.
       if (!$new_parent->getHasSubprojects()) {
         $member_type = PhabricatorProjectProjectHasMemberEdgeType::EDGECONST;
 
         $project_members = PhabricatorEdgeQuery::loadDestinationPHIDs(
           $new_parent->getPHID(),
           $member_type);
 
         if ($project_members) {
           $editor = id(new PhabricatorEdgeEditor());
           foreach ($project_members as $phid) {
             $editor->addEdge($object->getPHID(), $member_type, $phid);
           }
           $editor->save();
         }
       }
     }
 
     // TODO: We should dump an informational transaction onto the parent
     // project to show that we created the sub-thing.
 
     if ($materialize) {
       id(new PhabricatorProjectsMembershipIndexEngineExtension())
         ->rematerialize($object);
     }
 
     if ($new_parent) {
       id(new PhabricatorProjectsMembershipIndexEngineExtension())
         ->rematerialize($new_parent);
     }
 
     // See PHI1046. Milestones are always in the Space of their parent project.
     // Synchronize the database values to match the application values.
     $conn = $object->establishConnection('w');
     queryfx(
       $conn,
       'UPDATE %R SET spacePHID = %ns
         WHERE parentProjectPHID = %s AND milestoneNumber IS NOT NULL',
       $object,
       $object->getSpacePHID(),
       $object->getPHID());
 
     return parent::applyFinalEffects($object, $xactions);
   }
 
   public function addSlug(PhabricatorProject $project, $slug, $force) {
     $slug = PhabricatorSlug::normalizeProjectSlug($slug);
     $table = new PhabricatorProjectSlug();
     $project_phid = $project->getPHID();
 
     if ($force) {
       // If we have the `$force` flag set, we only want to ignore an existing
       // slug if it's for the same project. We'll error on collisions with
       // other projects.
       $current = $table->loadOneWhere(
         'slug = %s AND projectPHID = %s',
         $slug,
         $project_phid);
     } else {
       // Without the `$force` flag, we'll just return without doing anything
       // if any other project already has the slug.
       $current = $table->loadOneWhere(
         'slug = %s',
         $slug);
     }
 
     if ($current) {
       return;
     }
 
     return id(new PhabricatorProjectSlug())
       ->setSlug($slug)
       ->setProjectPHID($project_phid)
       ->save();
   }
 
   public function removeSlugs(PhabricatorProject $project, array $slugs) {
     if (!$slugs) {
       return;
     }
 
     // We're going to try to delete both the literal and normalized versions
     // of all slugs. This allows us to destroy old slugs that are no longer
     // valid.
     foreach ($this->normalizeSlugs($slugs) as $slug) {
       $slugs[] = $slug;
     }
 
     $objects = id(new PhabricatorProjectSlug())->loadAllWhere(
       'projectPHID = %s AND slug IN (%Ls)',
       $project->getPHID(),
       $slugs);
 
     foreach ($objects as $object) {
       $object->delete();
     }
   }
 
   public function normalizeSlugs(array $slugs) {
     foreach ($slugs as $key => $slug) {
       $slugs[$key] = PhabricatorSlug::normalizeProjectSlug($slug);
     }
 
     $slugs = array_unique($slugs);
     $slugs = array_values($slugs);
 
     return $slugs;
   }
 
   protected function adjustObjectForPolicyChecks(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $copy = parent::adjustObjectForPolicyChecks($object, $xactions);
 
     $type_edge = PhabricatorTransactions::TYPE_EDGE;
     $edgetype_member = PhabricatorProjectProjectHasMemberEdgeType::EDGECONST;
 
     // See T13462. If we're creating a milestone, set a dummy milestone
     // number so the project behaves like a milestone and uses milestone
     // policy rules. Otherwise, we'll end up checking the default policies
     // (which are not relevant to milestones) instead of the parent project
     // policies (which are the correct policies).
     if ($this->getIsMilestone() && !$copy->isMilestone()) {
       $copy->setMilestoneNumber(1);
     }
 
-    $member_xaction = null;
-    foreach ($xactions as $xaction) {
-      if ($xaction->getTransactionType() !== $type_edge) {
-        continue;
-      }
+    $hint = null;
+    if ($this->getIsMilestone()) {
+      // See T13462. If we're creating a milestone, predict that the members
+      // of the newly created milestone will be the same as the members of the
+      // parent project, since this is the governing rule.
+
+      $parent = $copy->getParentProject();
+
+      $parent = id(new PhabricatorProjectQuery())
+        ->setViewer($this->getActor())
+        ->withPHIDs(array($parent->getPHID()))
+        ->needMembers(true)
+        ->executeOne();
+      $members = $parent->getMemberPHIDs();
+
+      $hint = array_fuse($members);
+    } else {
+      $member_xaction = null;
+      foreach ($xactions as $xaction) {
+        if ($xaction->getTransactionType() !== $type_edge) {
+          continue;
+        }
+
+        $edgetype = $xaction->getMetadataValue('edge:type');
+        if ($edgetype !== $edgetype_member) {
+          continue;
+        }
 
-      $edgetype = $xaction->getMetadataValue('edge:type');
-      if ($edgetype !== $edgetype_member) {
-        continue;
+        $member_xaction = $xaction;
       }
 
-      $member_xaction = $xaction;
-    }
+      if ($member_xaction) {
+        $object_phid = $object->getPHID();
+
+        if ($object_phid) {
+          $project = id(new PhabricatorProjectQuery())
+            ->setViewer($this->getActor())
+            ->withPHIDs(array($object_phid))
+            ->needMembers(true)
+            ->executeOne();
+          $members = $project->getMemberPHIDs();
+        } else {
+          $members = array();
+        }
 
-    if ($member_xaction) {
-      $object_phid = $object->getPHID();
-
-      if ($object_phid) {
-        $project = id(new PhabricatorProjectQuery())
-          ->setViewer($this->getActor())
-          ->withPHIDs(array($object_phid))
-          ->needMembers(true)
-          ->executeOne();
-        $members = $project->getMemberPHIDs();
-      } else {
-        $members = array();
+        $clone_xaction = clone $member_xaction;
+        $hint = $this->getPHIDTransactionNewValue($clone_xaction, $members);
+        $hint = array_fuse($hint);
       }
+    }
 
-      $clone_xaction = clone $member_xaction;
-      $hint = $this->getPHIDTransactionNewValue($clone_xaction, $members);
+    if ($hint !== null) {
       $rule = new PhabricatorProjectMembersPolicyRule();
-
-      $hint = array_fuse($hint);
-
       PhabricatorPolicyRule::passTransactionHintToRule(
         $copy,
         $rule,
         $hint);
     }
 
     return $copy;
   }
 
   protected function expandTransactions(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     $actor = $this->getActor();
     $actor_phid = $actor->getPHID();
 
     $results = parent::expandTransactions($object, $xactions);
 
     $is_milestone = $object->isMilestone();
     foreach ($xactions as $xaction) {
       switch ($xaction->getTransactionType()) {
         case PhabricatorProjectMilestoneTransaction::TRANSACTIONTYPE:
           if ($xaction->getNewValue() !== null) {
             $is_milestone = true;
           }
           break;
       }
     }
 
     $this->setIsMilestone($is_milestone);
 
     return $results;
   }
 
   protected function shouldApplyHeraldRules(
     PhabricatorLiskDAO $object,
     array $xactions) {
     return true;
   }
 
   protected function buildHeraldAdapter(
     PhabricatorLiskDAO $object,
     array $xactions) {
 
     // Herald rules may run on behalf of other users and need to execute
     // membership checks against ancestors.
     $project = id(new PhabricatorProjectQuery())
       ->setViewer(PhabricatorUser::getOmnipotentUser())
       ->withPHIDs(array($object->getPHID()))
       ->needAncestorMembers(true)
       ->executeOne();
 
     return id(new PhabricatorProjectHeraldAdapter())
       ->setProject($project);
   }
 
 }