diff -r 205c3c6c1a51 -r 6ba79cf34f5e mercurial/mdiff.py
--- a/mercurial/mdiff.py	Thu Sep 22 18:23:58 2016 +0900
+++ b/mercurial/mdiff.py	Thu Oct 26 00:13:38 2017 +0900
@@ -67,6 +67,7 @@
         'ignoreblanklines': False,
         'upgrade': False,
         'showsimilarity': False,
+        'worddiff': False,
         }
 
     def __init__(self, **opts):