diff -r 486dbd6afa57 -r 99c5922b1641 mercurial/configitems.py
--- a/mercurial/configitems.py	Sun Oct 08 21:41:10 2017 +0200
+++ b/mercurial/configitems.py	Sun Oct 08 21:36:26 2017 +0200
@@ -149,6 +149,9 @@
 coreconfigitem('devel', 'warn-config',
     default=None,
 )
+coreconfigitem('devel', 'warn-config-default',
+    default=None,
+)
 coreconfigitem('diff', 'nodates',
     default=None,
 )