--- a/mercurial/util.py	Wed Apr 06 22:35:52 2016 +0000
+++ b/mercurial/util.py	Wed Apr 06 20:31:31 2016 +0000
@@ -49,6 +49,7 @@
 for attr in (
     'empty',
     'queue',
+    'stringio',
 ):
     globals()[attr] = getattr(pycompat, attr)