Use most recent transaction in Conpherence notification menu

Summary: Not sure this ever worked correctly, but now once we have a supported action, skip the rest of the transactions. Currently you'll see a random old post.

Test Plan: Test multiple rooms in various states with new messages, edits, new room titles, etc.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Differential Revision: https://secure.phabricator.com/D16660

src/applications/conpherence/storage/ConpherenceThread.php

@@ -286,6 +286,9 @@ final class ConpherenceThread extends ConpherenceDAO
       $message_transaction = null;
       $action_transaction = null;
       foreach ($transactions as $transaction) {
+        if ($message_transaction || $action_transaction) {
+          break;
+        }
         switch ($transaction->getTransactionType()) {
           case PhabricatorTransactions::TYPE_COMMENT:
             $message_transaction = $transaction;