diff -r 05c2a9f37a1d -r dc91580a0a88 mercurial/configitems.py
--- a/mercurial/configitems.py	Thu Oct 05 15:11:34 2017 +0200
+++ b/mercurial/configitems.py	Fri Oct 06 16:15:24 2017 +0200
@@ -158,6 +158,9 @@
 coreconfigitem('devel', 'warn-config-default',
     default=None,
 )
+coreconfigitem('devel', 'user.obsmarker',
+    default=None,
+)
 coreconfigitem('diff', 'nodates',
     default=None,
 )