--- a/mercurial/configitems.py	Thu Sep 22 18:23:58 2016 +0900
+++ b/mercurial/configitems.py	Thu Oct 26 00:13:38 2017 +0900
@@ -481,6 +481,9 @@
 coreconfigitem('experimental', 'evolution.track-operation',
     default=True,
 )
+coreconfigitem('experimental', 'worddiff',
+    default=False,
+)
 coreconfigitem('experimental', 'maxdeltachainspan',
     default=-1,
 )