diff -r cd7276f7ea83 -r 42ead5b3aa7b mercurial/util.py
--- a/mercurial/util.py	Sat Oct 01 15:10:38 2016 -0400
+++ b/mercurial/util.py	Sun Oct 02 03:38:14 2016 +0530
@@ -561,7 +561,7 @@
     Holds a reference to nodes on either side as well as a key-value
     pair for the dictionary entry.
     """
-    __slots__ = ('next', 'prev', 'key', 'value')
+    __slots__ = (u'next', u'prev', u'key', u'value')
 
     def __init__(self):
         self.next = None