Maniphest - fix bug updating tasks with blocked relationships

Summary: Ref T5604. Found this trying to open T5604 live. Basically this internal query needs the needSubscriberPHID set to true.

Test Plan: doing it live

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T5604

Differential Revision: https://secure.phabricator.com/D10975

src/applications/maniphest/editor/ManiphestTransactionEditor.php

@@ -369,6 +369,7 @@ final class ManiphestTransactionEditor
         $blocked_tasks = id(new ManiphestTaskQuery())
           ->setViewer($this->getActor())
           ->withPHIDs($blocked_phids)
+          ->needSubscriberPHIDs(true)
           ->execute();
 
         $old = $unblock_xaction->getOldValue();