PRESUBMIT: Make BUG= field mandatory.

PRESUBMIT.py

 # Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import json
 import os
@@ skipping 428 matching lines @@
         'You added one or more #includes that violate checkdeps rules.',
         error_descriptions))
   if warning_descriptions:
     results.append(output_api.PresubmitPromptOrNotify(
         'You added one or more #includes of files that are temporarily\n'
         'allowed but being removed. Can you avoid introducing the\n'
         '#include? See relevant DEPS file(s) for details and contacts.',
         warning_descriptions))
   return results
 
+def _CheckChangeHasBugField(input_api, output_api):
+  """Requires that the changelist have a BUG= field.
+
+  This check is stricter than the one in depot_tools/presubmit_canned_checks.py
+  since it fails the presubmit if the BUG= field is missing or doesn't contain
+  a bug reference.
+  """
+  if input_api.change.BUG:
+    return []
+  else:
+    return [output_api.PresubmitError(
+        'The BUG=[bug number] field is mandatory. Please create a bug and '
+        'reference it using either of:\n'
+        ' * https://bugs.webrtc.org - reference it using BUG=webrtc:XXXX\n'
+        ' * https://crbug.com - reference it using BUG=chromium:XXXXXX')]
 
 def _CheckJSONParseErrors(input_api, output_api):
   """Check that JSON files do not contain syntax errors."""
 
   def FilterFile(affected_file):
     return input_api.os_path.splitext(affected_file.LocalPath())[1] == '.json'
 
   def GetJSONParseError(input_api, filename):
     try:
       contents = input_api.ReadFile(filename)
@@ skipping 128 matching lines @@
 
 def CheckChangeOnCommit(input_api, output_api):
   results = []
   results.extend(_CommonChecks(input_api, output_api))
   results.extend(_VerifyNativeApiHeadersListIsValid(input_api, output_api))
   results.extend(input_api.canned_checks.CheckOwners(input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeWasUploaded(
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasDescription(
       input_api, output_api))
-  results.extend(input_api.canned_checks.CheckChangeHasBugField(
-      input_api, output_api))
+  results.extend(_CheckChangeHasBugField(input_api, output_api))
   results.extend(input_api.canned_checks.CheckChangeHasTestField(
       input_api, output_api))
   results.extend(input_api.canned_checks.CheckTreeIsOpen(
       input_api, output_api,
       json_url='http://webrtc-status.appspot.com/current?format=json'))
   return results
 
 
 # pylint: disable=W0613
 def GetPreferredTryMasters(project, change):
@@ skipping 11 matching lines @@
     for builder in masters[master]:
       if 'presubmit' in builder:
         # Do not trigger presubmit builders, since they're likely to fail
         # (e.g. OWNERS checks before finished code review), and we're running
         # local presubmit anyway.
         pass
       else:
         try_config[master][builder] = ['defaulttests']
 
   return try_config