--- a/mercurial/configitems.py	Mon Jul 10 21:49:37 2017 +0200
+++ b/mercurial/configitems.py	Fri Jun 30 03:44:43 2017 +0200
@@ -439,6 +439,9 @@
 coreconfigitem('ui', 'debugger',
     default=None,
 )
+coreconfigitem('ui', 'fallbackencoding',
+    default=None,
+)
 coreconfigitem('ui', 'forcemerge',
     default=None,
 )