get_depends_on_patchset is actually a POST endpoint

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 71 matching lines @@
       url += '?messages=true'
     data = json.loads(self.get(url, retry_on_404=True))
     data['description'] = '\n'.join(data['description'].strip().splitlines())
     return data
 
   def get_depends_on_patchset(self, issue, patchset):
     """Returns the patchset this patchset depends on if it exists."""
     url = '/%d/patchset/%d/get_depends_on_patchset' % (issue, patchset)
     resp = None
     try:
-      resp = json.loads(self.get(url))
+      resp = json.loads(self.post(url, []))
     except (urllib2.HTTPError, ValueError):
       # The get_depends_on_patchset endpoint does not exist on this Rietveld
       # instance yet. Ignore the error and proceed.
       # TODO(rmistry): Make this an error when all Rietveld instances have
       # this endpoint.
       pass
     return resp
 
   def get_patchset_properties(self, issue, patchset):
     """Returns the patchset properties."""
@@ skipping 614 matching lines @@
       self, issue, patchset, reason, clobber, revision, builders_and_tests,
       master=None, category='cq'):
     logging.info('ReadOnlyRietveld: triggering try jobs %r for issue %d' %
         (builders_and_tests, issue))
 
   def trigger_distributed_try_jobs(  # pylint:disable=R0201
       self, issue, patchset, reason, clobber, revision, masters,
       category='cq'):
     logging.info('ReadOnlyRietveld: triggering try jobs %r for issue %d' %
         (masters, issue))