Use functools.reduce() in difflib instead of __builtin__.reduce() to silence

warnings when running under -3.

Lib/difflib.py

@@ -34,6 +34,7 @@
 
 import heapq
 from collections import namedtuple as _namedtuple
+from functools import reduce
 
 Match = _namedtuple('Match', 'a b size')