diff -r 2d84947cd85d -r 4462a981e8df mercurial/mdiff.py
--- a/mercurial/mdiff.py	Tue May 02 17:05:22 2017 +0900
+++ b/mercurial/mdiff.py	Wed Apr 26 21:56:47 2017 +0900
@@ -13,7 +13,6 @@
 
 from .i18n import _
 from . import (
-    base85,
     bdiff,
     error,
     mpatch,
@@ -430,7 +429,7 @@
             l = chr(ord('A') + l - 1)
         else:
             l = chr(l - 26 + ord('a') - 1)
-        return '%c%s\n' % (l, base85.b85encode(line, True))
+        return '%c%s\n' % (l, util.b85encode(line, True))
 
     def chunk(text, csize=52):
         l = len(text)