Reload subscribers before sending mail, etc

Summary: Fixes T4629. CCs added by Herald don't get added to the cached subscriber list. Just reload subscribers before sending mail to pick up effects.

Test Plan: Created an "always add X as CC" Herald rule for revisions, created a revision, saw them get initial mail.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: spicyj, epriestley

Maniphest Tasks: T4629

Differential Revision: https://secure.phabricator.com/D8565

src/applications/transactions/editor/PhabricatorApplicationTransactionEditor.php

@@ -695,6 +695,11 @@ abstract class PhabricatorApplicationTransactionEditor
       }
     }
 
+    // Before sending mail or publishing feed stories, reload the object
+    // subscribers to pick up changes caused by Herald (or by other side effects
+    // in various transaction phases).
+    $this->loadSubscribers($object);
+
     $this->loadHandles($xactions);
 
     $mail = null;