--- a/mercurial/pycompat.py	Fri Jun 03 21:49:26 2016 +0900
+++ b/mercurial/pycompat.py	Sat Jun 04 14:38:00 2016 +0530
@@ -11,6 +11,12 @@
 from __future__ import absolute_import
 
 try:
+    import cPickle as pickle
+    pickle.dumps
+except ImportError:
+    import pickle
+
+try:
     import cStringIO as io
     stringio = io.StringIO
 except ImportError: