--- a/mercurial/thirdparty/concurrent/futures/_base.py	Mon Apr 09 12:22:31 2018 -0700
+++ b/mercurial/thirdparty/concurrent/futures/_base.py	Mon Apr 09 12:23:48 2018 -0700
@@ -1,6 +1,8 @@
 # Copyright 2009 Brian Quinlan. All Rights Reserved.
 # Licensed to PSF under a Contributor Agreement.
 
+from __future__ import absolute_import
+
 import collections
 import logging
 import threading