diff --git a/src/applications/maniphest/controller/ManiphestTaskEditController.php b/src/applications/maniphest/controller/ManiphestTaskEditController.php
index 1f8451b839..a7a7dd3e1c 100644
--- a/src/applications/maniphest/controller/ManiphestTaskEditController.php
+++ b/src/applications/maniphest/controller/ManiphestTaskEditController.php
@@ -1,742 +1,750 @@
 <?php
 
 final class ManiphestTaskEditController extends ManiphestController {
 
   private $id;
 
   public function willProcessRequest(array $data) {
     $this->id = idx($data, 'id');
   }
 
   public function processRequest() {
 
     $request = $this->getRequest();
     $user = $request->getUser();
     $response_type = $request->getStr('responseType', 'task');
 
     $can_edit_assign = $this->hasApplicationCapability(
       ManiphestCapabilityEditAssign::CAPABILITY);
     $can_edit_policies = $this->hasApplicationCapability(
       ManiphestCapabilityEditPolicies::CAPABILITY);
     $can_edit_priority = $this->hasApplicationCapability(
       ManiphestCapabilityEditPriority::CAPABILITY);
     $can_edit_projects = $this->hasApplicationCapability(
       ManiphestCapabilityEditProjects::CAPABILITY);
     $can_edit_status = $this->hasApplicationCapability(
       ManiphestCapabilityEditStatus::CAPABILITY);
 
     $parent_task = null;
     $template_id = null;
 
     if ($this->id) {
       $task = id(new ManiphestTaskQuery())
         ->setViewer($user)
         ->requireCapabilities(
           array(
             PhabricatorPolicyCapability::CAN_VIEW,
             PhabricatorPolicyCapability::CAN_EDIT,
           ))
         ->withIDs(array($this->id))
         ->executeOne();
       if (!$task) {
         return new Aphront404Response();
       }
     } else {
       $task = ManiphestTask::initializeNewTask($user);
 
       // We currently do not allow you to set the task status when creating
       // a new task, although now that statuses are custom it might make
       // sense.
       $can_edit_status = false;
 
       // These allow task creation with defaults.
       if (!$request->isFormPost()) {
         $task->setTitle($request->getStr('title'));
 
         if ($can_edit_projects) {
           $projects = $request->getStr('projects');
           if ($projects) {
             $tokens = $request->getStrList('projects');
 
             $type_project = PhabricatorProjectPHIDTypeProject::TYPECONST;
             foreach ($tokens as $key => $token) {
               if (phid_get_type($token) == $type_project) {
                 // If this is formatted like a PHID, leave it as-is.
                 continue;
               }
 
               if (preg_match('/^#/', $token)) {
                 // If this already has a "#", leave it as-is.
                 continue;
               }
 
               // Add a "#" prefix.
               $tokens[$key] = '#'.$token;
             }
 
             $default_projects = id(new PhabricatorObjectQuery())
               ->setViewer($user)
               ->withNames($tokens)
               ->execute();
             $default_projects = mpull($default_projects, 'getPHID');
 
             if ($default_projects) {
               $task->setProjectPHIDs($default_projects);
             }
           }
         }
 
         if ($can_edit_priority) {
           $priority = $request->getInt('priority');
           if ($priority !== null) {
             $priority_map = ManiphestTaskPriority::getTaskPriorityMap();
             if (isset($priority_map[$priority])) {
                 $task->setPriority($priority);
             }
           }
         }
 
         $task->setDescription($request->getStr('description'));
 
         if ($can_edit_assign) {
           $assign = $request->getStr('assign');
           if (strlen($assign)) {
             $assign_user = id(new PhabricatorPeopleQuery())
               ->setViewer($user)
               ->withUsernames(array($assign))
               ->executeOne();
             if (!$assign_user) {
               $assign_user = id(new PhabricatorPeopleQuery())
                 ->setViewer($user)
                 ->withPHIDs(array($assign))
                 ->executeOne();
             }
 
             if ($assign_user) {
               $task->setOwnerPHID($assign_user->getPHID());
             }
           }
         }
       }
 
       $template_id = $request->getInt('template');
 
       // You can only have a parent task if you're creating a new task.
       $parent_id = $request->getInt('parent');
       if ($parent_id) {
         $parent_task = id(new ManiphestTaskQuery())
           ->setViewer($user)
           ->withIDs(array($parent_id))
           ->executeOne();
         if (!$template_id) {
           $template_id = $parent_id;
         }
       }
     }
 
     $errors = array();
     $e_title = true;
 
     $field_list = PhabricatorCustomField::getObjectFields(
       $task,
       PhabricatorCustomField::ROLE_EDIT);
     $field_list->setViewer($user);
     $field_list->readFieldsFromStorage($task);
 
     $aux_fields = $field_list->getFields();
 
     if ($request->isFormPost()) {
       $changes = array();
 
       $new_title = $request->getStr('title');
       $new_desc = $request->getStr('description');
       $new_status = $request->getStr('status');
 
       if (!$task->getID()) {
         $workflow = 'create';
       } else {
         $workflow = '';
       }
 
       $changes[ManiphestTransaction::TYPE_TITLE] = $new_title;
       $changes[ManiphestTransaction::TYPE_DESCRIPTION] = $new_desc;
 
       if ($can_edit_status) {
         $changes[ManiphestTransaction::TYPE_STATUS] = $new_status;
       } else if (!$task->getID()) {
         // Create an initial status transaction for the burndown chart.
         // TODO: We can probably remove this once Facts comes online.
         $changes[ManiphestTransaction::TYPE_STATUS] = $task->getStatus();
       }
 
       $owner_tokenizer = $request->getArr('assigned_to');
       $owner_phid = reset($owner_tokenizer);
 
       if (!strlen($new_title)) {
         $e_title = pht('Required');
         $errors[] = pht('Title is required.');
       }
 
       $old_values = array();
       foreach ($aux_fields as $aux_arr_key => $aux_field) {
         // TODO: This should be buildFieldTransactionsFromRequest() once we
         // switch to ApplicationTransactions properly.
 
         $aux_old_value = $aux_field->getOldValueForApplicationTransactions();
         $aux_field->readValueFromRequest($request);
         $aux_new_value = $aux_field->getNewValueForApplicationTransactions();
 
         // TODO: We're faking a call to the ApplicaitonTransaction validation
         // logic here. We need valid objects to pass, but they aren't used
         // in a meaningful way. For now, build User objects. Once the Maniphest
         // objects exist, this will switch over automatically. This is a big
         // hack but shouldn't be long for this world.
         $placeholder_editor = new PhabricatorUserProfileEditor();
 
         $field_errors = $aux_field->validateApplicationTransactions(
           $placeholder_editor,
           PhabricatorTransactions::TYPE_CUSTOMFIELD,
           array(
             id(new ManiphestTransaction())
               ->setOldValue($aux_old_value)
               ->setNewValue($aux_new_value),
           ));
 
         foreach ($field_errors as $error) {
           $errors[] = $error->getMessage();
         }
 
         $old_values[$aux_field->getFieldKey()] = $aux_old_value;
       }
 
       if ($errors) {
         $task->setTitle($new_title);
         $task->setDescription($new_desc);
         $task->setPriority($request->getInt('priority'));
         $task->setOwnerPHID($owner_phid);
         $task->setCCPHIDs($request->getArr('cc'));
         $task->setProjectPHIDs($request->getArr('projects'));
       } else {
 
         if ($can_edit_priority) {
           $changes[ManiphestTransaction::TYPE_PRIORITY] =
             $request->getInt('priority');
         }
         if ($can_edit_assign) {
           $changes[ManiphestTransaction::TYPE_OWNER] = $owner_phid;
         }
 
         $changes[ManiphestTransaction::TYPE_CCS] = $request->getArr('cc');
 
         if ($can_edit_projects) {
           $projects = $request->getArr('projects');
           $changes[ManiphestTransaction::TYPE_PROJECTS] =
             $projects;
           $column_phid = $request->getStr('columnPHID');
           // allow for putting a task in a project column at creation -only-
           if (!$task->getID() && $column_phid && $projects) {
             $column = id(new PhabricatorProjectColumnQuery())
               ->setViewer($user)
               ->withProjectPHIDs($projects)
               ->withPHIDs(array($column_phid))
               ->executeOne();
             if ($column) {
               $changes[ManiphestTransaction::TYPE_PROJECT_COLUMN] =
                 array(
                   'new' => array(
                     'projectPHID' => $column->getProjectPHID(),
                     'columnPHIDs' => array($column_phid)),
                   'old' => array(
                     'projectPHID' => $column->getProjectPHID(),
                     'columnPHIDs' => array()));
             }
           }
         }
 
         if ($can_edit_policies) {
           $changes[PhabricatorTransactions::TYPE_VIEW_POLICY] =
             $request->getStr('viewPolicy');
           $changes[PhabricatorTransactions::TYPE_EDIT_POLICY] =
             $request->getStr('editPolicy');
         }
 
         $template = new ManiphestTransaction();
         $transactions = array();
 
         foreach ($changes as $type => $value) {
           $transaction = clone $template;
           $transaction->setTransactionType($type);
           if ($type == ManiphestTransaction::TYPE_PROJECT_COLUMN) {
             $transaction->setNewValue($value['new']);
             $transaction->setOldValue($value['old']);
           } else {
             $transaction->setNewValue($value);
           }
           $transactions[] = $transaction;
         }
 
         if ($aux_fields) {
           foreach ($aux_fields as $aux_field) {
             $transaction = clone $template;
             $transaction->setTransactionType(
               PhabricatorTransactions::TYPE_CUSTOMFIELD);
             $aux_key = $aux_field->getFieldKey();
             $transaction->setMetadataValue('customfield:key', $aux_key);
             $old = idx($old_values, $aux_key);
             $new = $aux_field->getNewValueForApplicationTransactions();
 
             $transaction->setOldValue($old);
             $transaction->setNewValue($new);
 
             $transactions[] = $transaction;
           }
         }
 
         if ($transactions) {
           $is_new = !$task->getID();
 
           $event = new PhabricatorEvent(
             PhabricatorEventType::TYPE_MANIPHEST_WILLEDITTASK,
             array(
               'task'          => $task,
               'new'           => $is_new,
               'transactions'  => $transactions,
             ));
           $event->setUser($user);
           $event->setAphrontRequest($request);
           PhutilEventEngine::dispatchEvent($event);
 
           $task = $event->getValue('task');
           $transactions = $event->getValue('transactions');
 
           $editor = id(new ManiphestTransactionEditor())
             ->setActor($user)
             ->setContentSourceFromRequest($request)
             ->setContinueOnNoEffect(true)
             ->applyTransactions($task, $transactions);
 
           $event = new PhabricatorEvent(
             PhabricatorEventType::TYPE_MANIPHEST_DIDEDITTASK,
             array(
               'task'          => $task,
               'new'           => $is_new,
               'transactions'  => $transactions,
             ));
           $event->setUser($user);
           $event->setAphrontRequest($request);
           PhutilEventEngine::dispatchEvent($event);
         }
 
 
         if ($parent_task) {
           id(new PhabricatorEdgeEditor())
             ->setActor($user)
             ->addEdge(
               $parent_task->getPHID(),
               PhabricatorEdgeConfig::TYPE_TASK_DEPENDS_ON_TASK,
               $task->getPHID())
             ->save();
           $workflow = $parent_task->getID();
         }
 
         if ($request->isAjax()) {
           switch ($response_type) {
             case 'card':
               $owner = null;
               if ($task->getOwnerPHID()) {
                 $owner = id(new PhabricatorHandleQuery())
                   ->setViewer($user)
                   ->withPHIDs(array($task->getOwnerPHID()))
                   ->executeOne();
               }
               $tasks = id(new ProjectBoardTaskCard())
                 ->setViewer($user)
                 ->setTask($task)
                 ->setOwner($owner)
                 ->setCanEdit(true)
                 ->getItem();
               $column_phid = $request->getStr('columnPHID');
               $column = id(new PhabricatorProjectColumnQuery())
                 ->setViewer($user)
                 ->withPHIDs(array($column_phid))
                 ->executeOne();
               if ($column->isDefaultColumn()) {
                 $column_tasks = array();
                 $potential_col_tasks = id(new ManiphestTaskQuery())
                   ->setViewer($user)
                   ->withAllProjects(array($column->getProjectPHID()))
                   ->withStatuses(ManiphestTaskStatus::getOpenStatusConstants())
                   ->setOrderBy(ManiphestTaskQuery::ORDER_PRIORITY)
                   ->execute();
                 $potential_col_tasks = mpull(
                   $potential_col_tasks,
                   null,
                   'getPHID');
                 $potential_task_phids = array_keys($potential_col_tasks);
                 if ($potential_task_phids) {
                   $edge_type = PhabricatorEdgeConfig::TYPE_OBJECT_HAS_COLUMN;
                   $edge_query = id(new PhabricatorEdgeQuery())
                     ->withSourcePHIDs($potential_task_phids)
                     ->withEdgeTypes(array($edge_type));
                   $edges = $edge_query->execute();
                   foreach ($potential_col_tasks as $task_phid => $curr_task) {
                     $curr_column_phids = $edges[$task_phid][$edge_type];
                     $curr_column_phid = head_key($curr_column_phids);
                     if (!$curr_column_phid ||
                         $curr_column_phid == $column_phid) {
                       $column_tasks[] = $curr_task;
                     }
                   }
                 }
               } else {
                 $column_task_phids = PhabricatorEdgeQuery::loadDestinationPHIDs(
                   $column_phid,
                   PhabricatorEdgeConfig::TYPE_COLUMN_HAS_OBJECT);
                 $column_tasks = id(new ManiphestTaskQuery())
                   ->setViewer($user)
                   ->withPHIDs($column_task_phids)
                   ->withStatuses(ManiphestTaskStatus::getOpenStatusConstants())
                   ->setOrderBy(ManiphestTaskQuery::ORDER_PRIORITY)
                   ->execute();
               }
               $column_task_phids = mpull($column_tasks, 'getPHID');
               $task_phid = $task->getPHID();
               $after_phid = null;
               foreach ($column_task_phids as $phid) {
                 if ($phid == $task_phid) {
                   break;
                 }
                 $after_phid = $phid;
               }
               $data = array(
                 'insertAfterPHID' => $after_phid);
               break;
             case 'task':
             default:
               $tasks = $this->renderSingleTask($task);
               $data = array();
               break;
           }
           return id(new AphrontAjaxResponse())->setContent(
             array(
               'tasks' => $tasks,
               'data' => $data,
             ));
         }
 
         $redirect_uri = '/T'.$task->getID();
 
         if ($workflow) {
           $redirect_uri .= '?workflow='.$workflow;
         }
 
         return id(new AphrontRedirectResponse())
           ->setURI($redirect_uri);
       }
     } else {
       if (!$task->getID()) {
         $task->setCCPHIDs(array(
           $user->getPHID(),
         ));
         if ($template_id) {
           $template_task = id(new ManiphestTaskQuery())
             ->setViewer($user)
             ->withIDs(array($template_id))
             ->executeOne();
           if ($template_task) {
             $task->setCCPHIDs($template_task->getCCPHIDs());
             $task->setProjectPHIDs($template_task->getProjectPHIDs());
             $task->setOwnerPHID($template_task->getOwnerPHID());
             $task->setPriority($template_task->getPriority());
             $task->setViewPolicy($template_task->getViewPolicy());
             $task->setEditPolicy($template_task->getEditPolicy());
 
             $template_fields = PhabricatorCustomField::getObjectFields(
               $template_task,
               PhabricatorCustomField::ROLE_EDIT);
 
             $fields = $template_fields->getFields();
             foreach ($fields as $key => $field) {
               if (!$field->shouldCopyWhenCreatingSimilarTask()) {
                 unset($fields[$key]);
               }
               if (empty($aux_fields[$key])) {
                 unset($fields[$key]);
               }
             }
 
             if ($fields) {
               id(new PhabricatorCustomFieldList($fields))
                 ->setViewer($user)
                 ->readFieldsFromStorage($template_task);
 
               foreach ($fields as $key => $field) {
                 $aux_fields[$key]->setValueFromStorage(
                   $field->getValueForStorage());
               }
             }
           }
         }
       }
     }
 
     $phids = array_merge(
       array($task->getOwnerPHID()),
       $task->getCCPHIDs(),
       $task->getProjectPHIDs());
 
     if ($parent_task) {
       $phids[] = $parent_task->getPHID();
     }
 
     $phids = array_filter($phids);
     $phids = array_unique($phids);
 
     $handles = $this->loadViewerHandles($phids);
 
     $error_view = null;
     if ($errors) {
       $error_view = new AphrontErrorView();
       $error_view->setErrors($errors);
     }
 
     $priority_map = ManiphestTaskPriority::getTaskPriorityMap();
 
     if ($task->getOwnerPHID()) {
       $assigned_value = array($handles[$task->getOwnerPHID()]);
     } else {
       $assigned_value = array();
     }
 
     if ($task->getCCPHIDs()) {
       $cc_value = array_select_keys($handles, $task->getCCPHIDs());
     } else {
       $cc_value = array();
     }
 
     if ($task->getProjectPHIDs()) {
       $projects_value = array_select_keys($handles, $task->getProjectPHIDs());
     } else {
       $projects_value = array();
     }
 
     $cancel_id = nonempty($task->getID(), $template_id);
     if ($cancel_id) {
       $cancel_uri = '/T'.$cancel_id;
     } else {
       $cancel_uri = '/maniphest/';
     }
 
     if ($task->getID()) {
       $button_name = pht('Save Task');
       $header_name = pht('Edit Task');
     } else if ($parent_task) {
       $cancel_uri = '/T'.$parent_task->getID();
       $button_name = pht('Create Task');
       $header_name = pht('Create New Subtask');
     } else {
       $button_name = pht('Create Task');
       $header_name = pht('Create New Task');
     }
 
     require_celerity_resource('maniphest-task-edit-css');
 
     $project_tokenizer_id = celerity_generate_unique_node_id();
 
     $form = new AphrontFormView();
     $form
       ->setUser($user)
       ->addHiddenInput('template', $template_id)
       ->addHiddenInput('responseType', $response_type)
       ->addHiddenInput('columnPHID', $request->getStr('columnPHID'));
 
     if ($parent_task) {
       $form
         ->appendChild(
           id(new AphrontFormStaticControl())
             ->setLabel(pht('Parent Task'))
             ->setValue($handles[$parent_task->getPHID()]->getFullName()))
         ->addHiddenInput('parent', $parent_task->getID());
     }
 
     $form
       ->appendChild(
         id(new AphrontFormTextAreaControl())
           ->setLabel(pht('Title'))
           ->setName('title')
           ->setError($e_title)
           ->setHeight(AphrontFormTextAreaControl::HEIGHT_VERY_SHORT)
           ->setValue($task->getTitle()));
 
     if ($can_edit_status) {
+      // See T4819.
+      $status_map = ManiphestTaskStatus::getTaskStatusMap();
+      $dup_status = ManiphestTaskStatus::getDuplicateStatus();
+
+      if ($task->getStatus() != $dup_status) {
+        unset($status_map[$dup_status]);
+      }
+
       $form
         ->appendChild(
           id(new AphrontFormSelectControl())
             ->setLabel(pht('Status'))
             ->setName('status')
             ->setValue($task->getStatus())
-            ->setOptions(ManiphestTaskStatus::getTaskStatusMap()));
+            ->setOptions($status_map));
     }
 
     $policies = id(new PhabricatorPolicyQuery())
       ->setViewer($user)
       ->setObject($task)
       ->execute();
 
     if ($can_edit_assign) {
       $form->appendChild(
         id(new AphrontFormTokenizerControl())
           ->setLabel(pht('Assigned To'))
           ->setName('assigned_to')
           ->setValue($assigned_value)
           ->setUser($user)
           ->setDatasource('/typeahead/common/users/')
           ->setLimit(1));
     }
 
     $form
       ->appendChild(
         id(new AphrontFormTokenizerControl())
           ->setLabel(pht('CC'))
           ->setName('cc')
           ->setValue($cc_value)
           ->setUser($user)
           ->setDatasource('/typeahead/common/mailable/'));
 
     if ($can_edit_priority) {
       $form
         ->appendChild(
           id(new AphrontFormSelectControl())
             ->setLabel(pht('Priority'))
             ->setName('priority')
             ->setOptions($priority_map)
             ->setValue($task->getPriority()));
     }
 
     if ($can_edit_policies) {
       $form
         ->appendChild(
           id(new AphrontFormPolicyControl())
             ->setUser($user)
             ->setCapability(PhabricatorPolicyCapability::CAN_VIEW)
             ->setPolicyObject($task)
             ->setPolicies($policies)
             ->setName('viewPolicy'))
         ->appendChild(
           id(new AphrontFormPolicyControl())
             ->setUser($user)
             ->setCapability(PhabricatorPolicyCapability::CAN_EDIT)
             ->setPolicyObject($task)
             ->setPolicies($policies)
             ->setName('editPolicy'));
     }
 
     if ($can_edit_projects) {
       $form
         ->appendChild(
           id(new AphrontFormTokenizerControl())
             ->setLabel(pht('Projects'))
             ->setName('projects')
             ->setValue($projects_value)
             ->setID($project_tokenizer_id)
             ->setCaption(
               javelin_tag(
                 'a',
                 array(
                   'href'        => '/project/create/',
                   'mustcapture' => true,
                   'sigil'       => 'project-create',
                 ),
                 pht('Create New Project')))
             ->setDatasource('/typeahead/common/projects/'));
     }
 
     $field_list->appendFieldsToForm($form);
 
     require_celerity_resource('aphront-error-view-css');
 
     Javelin::initBehavior('project-create', array(
       'tokenizerID' => $project_tokenizer_id,
     ));
 
     $description_control = new PhabricatorRemarkupControl();
     // "Upsell" creating tasks via email in create flows if the instance is
     // configured for this awesomeness.
     $email_create = PhabricatorEnv::getEnvConfig(
       'metamta.maniphest.public-create-email');
     if (!$task->getID() && $email_create) {
       $email_hint = pht(
         'You can also create tasks by sending an email to: %s',
         phutil_tag('tt', array(), $email_create));
       $description_control->setCaption($email_hint);
     }
 
     $description_control
       ->setLabel(pht('Description'))
       ->setName('description')
       ->setID('description-textarea')
       ->setValue($task->getDescription())
       ->setUser($user);
 
     $form
       ->appendChild($description_control);
 
 
     if ($request->isAjax()) {
       $dialog = id(new AphrontDialogView())
         ->setUser($user)
         ->setWidth(AphrontDialogView::WIDTH_FULL)
         ->setTitle($header_name)
         ->appendChild(
           array(
             $error_view,
             $form->buildLayoutView(),
           ))
         ->addCancelButton($cancel_uri)
         ->addSubmitButton($button_name);
       return id(new AphrontDialogResponse())->setDialog($dialog);
     }
 
     $form
       ->appendChild(
         id(new AphrontFormSubmitControl())
           ->addCancelButton($cancel_uri)
           ->setValue($button_name));
 
     $form_box = id(new PHUIObjectBoxView())
       ->setHeaderText($header_name)
       ->setFormErrors($errors)
       ->setForm($form);
 
     $preview = id(new PHUIRemarkupPreviewPanel())
       ->setHeader(pht('Description Preview'))
       ->setControlID('description-textarea')
       ->setPreviewURI($this->getApplicationURI('task/descriptionpreview/'));
 
     if ($task->getID()) {
       $page_objects = array($task->getPHID());
     } else {
       $page_objects = array();
     }
 
     $crumbs = $this->buildApplicationCrumbs();
 
     if ($task->getID()) {
       $crumbs->addTextCrumb('T'.$task->getID(), '/T'.$task->getID());
     }
 
     $crumbs->addTextCrumb($header_name);
 
     return $this->buildApplicationPage(
       array(
         $crumbs,
         $form_box,
         $preview,
       ),
       array(
         'title' => $header_name,
         'pageObjects' => $page_objects,
         'device' => true,
       ));
   }
 }