Fix PostUploadHook for Gerrit issues

PRESUBMIT.py

 # Copyright (c) 2013 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.
 
 
 """Top-level presubmit script for Skia.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details about the presubmit API built into gcl.
 """
@@ skipping 440 matching lines @@
     if 'site' == file_path.split(os.path.sep)[0]:
       atleast_one_docs_change = True
     else:
       all_docs_changes = False
     if atleast_one_docs_change and not all_docs_changes:
       break
 
   issue = cl.issue
   if issue:
     original_description = cl.GetDescription()
+    changeIdLine = None
+    if cl.IsGerrit():
+      # Remove Change-Id from description and add it back at the end.
+      regex = re.compile(r'^(Change-Id: (\w+))(\n*)\Z', re.M | re.I)
+      changeIdLine = re.search(regex, original_description).group(0)
+      original_description = re.sub(regex, '', original_description)
+      original_description = re.sub('\n+\Z', '\n', original_description)
+
     new_description = original_description
 
     # Add GOLD_TRYBOT_URL if it does not exist yet.
     if not re.search(r'^GOLD_TRYBOT_URL=', new_description, re.M | re.I):
       new_description += '\nGOLD_TRYBOT_URL= %s%s' % (GOLD_TRYBOT_URL, issue)
       results.append(
           output_api.PresubmitNotifyResult(
               'Added link to Gold trybot runs to the CL\'s description.\n'
               'Note: Results may take sometime to be populated after trybots '
               'complete.'))
@@ skipping 57 matching lines @@
                   'Your CL modifies the path %s.\nAutomatically adding %s to '
                   'the CL description.' % (affected_file_path, extra_bots)))
           _MergeCQExtraTrybotsMaps(
               cq_master_to_trybots, _GetCQExtraTrybotsMap(extra_bots))
     if cq_master_to_trybots:
       new_description = _AddCQExtraTrybotsToDesc(
           cq_master_to_trybots, new_description)
 
     # If the description has changed update it.
     if new_description != original_description:
+      if changeIdLine:
+        # The Change-Id line must have two newlines before it.
+        new_description += '\n\n' + changeIdLine
       cl.UpdateDescription(new_description)
 
     return results
 
 
 def _AddCQExtraTrybotsToDesc(cq_master_to_trybots, description):
   """Adds the specified master and trybots to the CQ_INCLUDE_TRYBOTS keyword.
 
   If the keyword already exists in the description then it appends to it only
   if the specified values do not already exist.
@@ skipping 47 matching lines @@
     state and an error if it is in 'Closed' state.
   """
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   results.extend(
       _CheckTreeStatus(input_api, output_api, json_url=(
           SKIA_TREE_STATUS_URL + '/banner-status?format=json')))
   results.extend(_CheckLGTMsForPublicAPI(input_api, output_api))
   results.extend(_CheckOwnerIsInAuthorsFile(input_api, output_api))
   return results