Add support for A+ files.

rietveld.py

 # Copyright (c) 2011 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 137 matching lines @@
           except urllib2.HTTPError, e:
             if e.code == 404:
               raise patch.UnsupportedPatchFormat(
                   filename, 'File doesn\'t have a diff.')
             raise
           # It may happen on property-only change or svn copy without diff.
           if not diff:
             # Support this use case if it ever happen.
             raise patch.UnsupportedPatchFormat(
                 filename, 'Empty diff is not supported yet.\n')
-          out.append(patch.FilePatchDiff(filename, diff, svn_props))
+          p = patch.FilePatchDiff(filename, diff, svn_props)
+          out.append(p)
           if status[0] == 'A':
             # It won't be set for empty file.
-            out[-1].is_new = True
+            p.is_new = True
+          if status[1] == '+' and not (p.source_filename or p.svn_properties):
+            raise patch.UnsupportedPatchFormat(
+                filename, 'Failed to process the svn properties')
       else:
         raise patch.UnsupportedPatchFormat(
             filename, 'Change with status \'%s\' is not supported.' % status)
 
     return patch.PatchSet(out)
 
   @staticmethod
   def parse_svn_properties(rietveld_svn_props, filename):
     """Returns a list of tuple [('property', 'newvalue')].
 
@@ skipping 94 matching lines @@
         if retry >= (maxtries - 1):
           raise
         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)
 
   # DEPRECATED.
   Send = get