diff -r 625202a44d88 -r db935a5ea364 mercurial/configitems.py
--- a/mercurial/configitems.py	Wed Oct 11 04:14:33 2017 +0200
+++ b/mercurial/configitems.py	Wed Oct 11 04:14:44 2017 +0200
@@ -730,6 +730,9 @@
 coreconfigitem('web', 'cache',
     default=True,
 )
+coreconfigitem('web', 'contact',
+    default=None,
+)
 coreconfigitem('web', 'accesslog',
     default='-',
 )