Change the CQ code to update R= line as done in depot_tools.

pending_manager.py

 # coding=utf8
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 """Commit queue manager class.
 
 Security implications:
 
 The following hypothesis are made:
 - Commit queue:
@@ skipping 424 matching lines @@
 
     Do the checkout and applies the patch.
     """
     try:
       try:
         # Make sure to apply on HEAD.
         pending.revision = None
         pending.apply_patch(self.context, True)
         # Commit it.
         commit_desc = git_cl.ChangeDescription(pending.description)
+        props = {'reviewers': pending.reviewers, 'messages': pending.messages}
+        approving_reviewers = git_cl.get_approving_reviewers(props)
+        commit_desc.update_reviewers(approving_reviewers)
         if (self.context.server_hooks_missing and
             self.context.rietveld.email != pending.owner):
-          commit_desc.update_reviewers(pending.reviewers)
           commit_desc.append_footer('Author: ' + pending.owner)
         commit_desc.append_footer('Review URL: %s/%s' % (
             self.context.rietveld.url,
             pending.issue))
         pending.revision = self.context.checkout.commit(
             commit_desc.description, pending.owner)
         if not pending.revision:
           raise base.DiscardPending(pending, 'Failed to commit patch.')
 
         # Note that the commit succeeded for commit throttling.
         self.recent_commit_timestamps.append(time.time())
         self.recent_commit_timestamps = (
             self.recent_commit_timestamps[-(self.MAX_COMMIT_BURST + 1):])
 
         viewvc_url = self.context.checkout.get_settings('VIEW_VC')
         issue_desc = git_cl.ChangeDescription(pending.description)
+        issue_desc.update_reviewers(approving_reviewers)
         msg = 'Committed: %s' % pending.revision
         if viewvc_url:
           viewvc_url = '%s%s' % (viewvc_url.rstrip('/'), pending.revision)
           msg = 'Committed: %s' % viewvc_url
           issue_desc.append_footer(msg)
 
         # Update the CQ dashboard.
         self.context.status.send(
             pending,
             { 'verification': 'commit',
@@ skipping 68 matching lines @@
     """Loads the commit queue state from a JSON file."""
     self.queue = model.load_from_json_file(filename)
 
   def save(self, filename):
     """Save the commit queue state in a simple JSON file."""
     model.save_to_json_file(filename, self.queue)
 
   def close(self):
     """Close all the active pending manager items."""
     self.context.status.close()