diff -r 008d37c4d783 -r 3b88a7fa97d8 mercurial/mdiff.py
--- a/mercurial/mdiff.py	Sat Aug 13 12:08:23 2016 +0900
+++ b/mercurial/mdiff.py	Sat Aug 13 12:12:50 2016 +0900
@@ -13,13 +13,15 @@
 
 from .i18n import _
 from . import (
-    bdiff,
     error,
     mpatch,
+    policy,
     pycompat,
     util,
 )
 
+bdiff = policy.importmod(r'bdiff')
+
 blocks = bdiff.blocks
 fixws = bdiff.fixws
 patches = mpatch.patches