Fix for single line file modification

patch.py

 # coding=utf8
 # 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.
 """Utility functions to handle patches."""
 
 import posixpath
 import os
 import re
 
@@ skipping 201 matching lines @@
     # http://codereview.chromium.org/download/issue6250123_3013_6010.diff
     # Rename no change:
     # http://codereview.chromium.org/download/issue6287022_3001_4010.diff
     return any(l.startswith('diff --git') for l in diff_header.splitlines())
 
   def _split_hunks(self):
     """Splits the hunks and does verification."""
     hunks = []
     for line in self.diff_hunks.splitlines(True):
       if line.startswith('@@'):
-        match = re.match(r'^@@ -(\d+),(\d+) \+([\d,]+) @@.*$', line)
+        match = re.match(r'^@@ -([\d,]+) \+([\d,]+) @@.*$', line)
         # File add will result in "-0,0 +1" but file deletion will result in
         # "-1,N +0,0" where N is the number of lines deleted. That's from diff
         # and svn diff. git diff doesn't exhibit this behavior.
+        # svn diff for a single line file rewrite "@@ -1 +1 @@". Fun.
         if not match:
           self._fail('Hunk header is unparsable')
-        if ',' in match.group(3):
-          start_dst, lines_dst = map(int, match.group(3).split(',', 1))
+        if ',' in match.group(1):
+          start_src, lines_src = map(int, match.group(1).split(',', 1))
         else:
-          start_dst = int(match.group(3))
+          start_src = int(match.group(1))
+          lines_src = 0
+        if ',' in match.group(2):
+          start_dst, lines_dst = map(int, match.group(2).split(',', 1))
+        else:
+          start_dst = int(match.group(2))
           lines_dst = 0
-        new_hunk = Hunk(int(match.group(1)), int(match.group(2)),
-                        start_dst, lines_dst)
+        new_hunk = Hunk(start_src, lines_src, start_dst, lines_dst)
         if hunks:
           if new_hunk.start_src <= hunks[-1].start_src:
             self._fail('Hunks source lines are not ordered')
           if new_hunk.start_dst <= hunks[-1].start_dst:
             self._fail('Hunks destination lines are not ordered')
         hunks.append(new_hunk)
         continue
       hunks[-1].text.append(line)
 
     if len(hunks) == 1:
@@ skipping 244 matching lines @@
   def __iter__(self):
     for patch in self.patches:
       yield patch
 
   def __getitem__(self, key):
     return self.patches[key]
 
   @property
   def filenames(self):
     return [p.filename for p in self.patches]