diff -r 15ddf83fbf84 -r cb0db11f392d mercurial/context.py
--- a/mercurial/context.py	Fri Dec 29 05:35:57 2017 +0530
+++ b/mercurial/context.py	Fri Dec 29 03:32:04 2017 +0530
@@ -1122,7 +1122,7 @@
                 hist[f] = curr
                 del pcache[f]
 
-        return zip(hist[base][0], hist[base][1].splitlines(True))
+        return pycompat.ziplist(hist[base][0], hist[base][1].splitlines(True))
 
     def ancestors(self, followfirst=False):
         visit = {}