There is no reason to not assume that status:null isn't 'M'.

rietveld.py

 # 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:
   - Nobody else than issue owner can upload a patch set
@@ skipping 91 matching lines @@
     """
     url = '/download/issue%s_%s_%s.diff' % (issue, patchset, item)
     return self.get(url)
 
   def get_patch(self, issue, patchset):
     """Returns a PatchSet object containing the details to apply this patch."""
     props = self.get_patchset_properties(issue, patchset) or {}
     out = []
     for filename, state in props.get('files', {}).iteritems():
       logging.debug('%s' % filename)
-      status = state.get('status')
-      if not status:
-        raise patch.UnsupportedPatchFormat(
-            filename, 'File\'s status is None, patchset upload is incomplete.')
+      # If not status, just assume it's a 'M'. Rietveld often gets it wrong and
+      # just has status: null. Oh well.
+      status = state.get('status') or 'M'
       if status[0] not in ('A', 'D', 'M'):
         raise patch.UnsupportedPatchFormat(
             filename, 'Change with status \'%s\' is not supported.' % status)
 
       svn_props = self.parse_svn_properties(
           state.get('property_changes', ''), filename)
 
       if state.get('is_binary'):
         if status[0] == 'D':
           if status[0] != status.strip():
@@ skipping 206 matching lines @@
           if not 'Name or service not known' in e.reason:
             # Usually internal GAE flakiness.
             raise
         # If reaching this line, loop again. Uses a small backoff.
         time.sleep(1+maxtries*2)
     finally:
       upload.ErrorExit = old_error_exit
 
   # DEPRECATED.
   Send = get