Find the HASHTAGS file even if you are not at the checkout root

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 374 matching lines @@
                 'CL\'s description'))
       if not re.search(
           r'^NOTRY=true$', new_description, re.M | re.I):
         new_description += "\nNOTRY=true"
         results.append(
             output_api.PresubmitNotifyResult(
                 'Trybots do not yet work for non-master branches. '
                 'Automatically added \'NOTRY=true\' to the CL\'s description'))
 
     # Read and process the HASHTAGS file.
-    with open('HASHTAGS', 'rb') as hashtags_csv:
+    hashtags_fullpath = os.path.join(change._local_root, 'HASHTAGS')
+    with open(hashtags_fullpath, 'rb') as hashtags_csv:
       hashtags_reader = csv.reader(hashtags_csv, delimiter=',')
       for row in hashtags_reader:
         if not row or row[0].startswith('#'):
           # Ignore empty lines and comments
           continue
         hashtag = row[0]
         # Search for the hashtag in the description.
         if re.search('#%s' % hashtag, new_description, re.M | re.I):
           for mapped_text in row[1:]:
             # Special case handling for CQ_KEYWORDS_THAT_NEED_APPENDING.
@@ skipping 55 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