--- a/mercurial/util.py	Fri Aug 05 14:15:45 2016 +0200
+++ b/mercurial/util.py	Thu Mar 16 04:53:23 2017 +0530
@@ -2920,7 +2920,7 @@
             del dirs[base]
 
     def __iter__(self):
-        return self._dirs.iterkeys()
+        return iter(self._dirs)
 
     def __contains__(self, d):
         return d in self._dirs