merge in fixes for python 2.5

owners.py

 # Copyright (c) 2010 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.
 
 """A database of OWNERS files."""
 
 import collections
 import re
 
 
 # If this is present by itself on a line, this means that everyone can review.
 EVERYONE = '*'
 
 
 # Recognizes 'X@Y' email addresses. Very simplistic.
 BASIC_EMAIL_REGEXP = r'^[\w\-\+\%\.]+\@[\w\-\+\%\.]+$'
 
 
 def _assert_is_collection(obj):
-  assert (isinstance(obj, collections.Iterable) and
-          isinstance(obj, collections.Sized) and
-          not isinstance(obj, basestring))
+  assert not isinstance(obj, basestring)
+  if hasattr(collections, 'Iterable') and hasattr(collections, 'Sized'):
+    assert (isinstance(obj, collections.Iterable) and
+            isinstance(obj, collections.Sized))
 
 
 class SyntaxErrorInOwnersFile(Exception):
   def __init__(self, path, lineno, msg):
     super(SyntaxErrorInOwnersFile, self).__init__((path, lineno, msg))
     self.path = path
     self.lineno = lineno
     self.msg = msg
 
   def __str__(self):
@@ skipping 133 matching lines @@
     # short combinations of owners.
     every_owner = set()
     for f in files:
       dirname = self.os_path.dirname(f)
       while dirname in self.owners_for:
         every_owner |= self.owners_for[dirname]
         if self._stop_looking(dirname):
           break
         dirname = self.os_path.dirname(dirname)
     return every_owner