Maybe fix excluding to / cc folks on differential emails

Summary: Ref T5185. By code inspection, I am pretty sure before this patch it was doing a set of a get on itself which does nothing. Now, being careful not to break Facebook we get the proper exclusion phids. I am pretty sure the folks in T5185 are experiencing this in Differential only.

Test Plan: Get some folks on T5185 to play with this

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: epriestley, Korvin

Maniphest Tasks: T5185

Differential Revision: https://secure.phabricator.com/D10087

src/applications/differential/mail/DifferentialReplyHandler.php

@@ -146,15 +146,21 @@ class DifferentialReplyHandler extends PhabricatorMailReplyHandler {
             ->setContent($body));
     }
 
-    $editor = id(new DifferentialTransactionEditor())
-      ->setActor($actor)
-      ->setExcludeMailRecipientPHIDs($this->getExcludeMailRecipientPHIDs())
-      ->setContinueOnMissingFields(true)
-      ->setContinueOnNoEffect(true);
-
     // NOTE: We have to be careful about this because Facebook's
     // implementation jumps straight into handleAction() and will not have
     // a PhabricatorMetaMTAReceivedMail object.
+    if ($this->receivedMail) {
+      $exclude = $this->receivedMail->getExcludeMailRecipientPHIDs();
+    } else {
+      $exclude = $this->getExcludeMailRecipientPHIDs();
+    }
+
+    $editor = id(new DifferentialTransactionEditor())
+      ->setActor($actor)
+      ->setExcludeMailRecipientPHIDs($exclude)
+      ->setContinueOnMissingFields(true)
+      ->setContinueOnNoEffect(true);
+
     if ($this->receivedMail) {
       $content_source = PhabricatorContentSource::newForSource(
         PhabricatorContentSource::SOURCE_EMAIL,