Always convert flag value to string in set_flag

rietveld.py

 # coding: utf-8
 # 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.
 """Defines class Rietveld to easily access a rietveld instance.
 
 Security implications:
 
 The following hypothesis are made:
 - Rietveld enforces:
@@ skipping 239 matching lines @@
         ('message', message),
         ('message_only', 'True'),
         ('add_as_reviewer', str(bool(add_as_reviewer))),
         ('send_mail', 'True'),
         ('no_redirect', 'True')])
 
   def set_flag(self, issue, patchset, flag, value):
     return self.post('/%d/edit_flags' % issue, [
         ('last_patchset', str(patchset)),
         ('xsrf_token', self.xsrf_token()),
-        (flag, value)])
+        (flag, str(value))])
 
   def search(
       self,
       owner=None, reviewer=None,
       base=None,
       closed=None, private=None, commit=None,
       created_before=None, created_after=None,
       modified_before=None, modified_after=None,
       per_request=None, keys_only=False,
       with_messages=False):
@@ skipping 241 matching lines @@
 
   def set_flag(self, issue, patchset, flag, value):  # pylint:disable=R0201
     logging.info('ReadOnlyRietveld: setting flag "%s" to "%s" for issue %d' %
         (flag, value, issue))
     ReadOnlyRietveld._local_changes.setdefault(issue, {})[flag] = value
 
   def trigger_try_jobs(  # pylint:disable=R0201
       self, issue, patchset, reason, clobber, revision, builders_and_tests):
     logging.info('ReadOnlyRietveld: triggering try jobs %r for issue %d' %
         (builders_and_tests, issue))