diff -r de4a80a2b45c -r b501579147f1 mercurial/formatter.py
--- a/mercurial/formatter.py	Fri Jun 03 21:49:26 2016 +0900
+++ b/mercurial/formatter.py	Sat Jun 04 14:38:00 2016 +0530
@@ -7,7 +7,6 @@
 
 from __future__ import absolute_import
 
-import cPickle
 import os
 
 from .i18n import _
@@ -20,8 +19,11 @@
     encoding,
     error,
     templater,
+    util,
 )
 
+pickle = util.pickle
+
 class baseformatter(object):
     def __init__(self, ui, topic, opts):
         self._ui = ui
@@ -107,7 +109,7 @@
         self._data.append(self._item)
     def end(self):
         baseformatter.end(self)
-        self._ui.write(cPickle.dumps(self._data))
+        self._ui.write(pickle.dumps(self._data))
 
 def _jsonifyobj(v):
     if isinstance(v, tuple):