--- a/mercurial/configitems.py	Sat Jul 01 21:57:17 2017 +0200
+++ b/mercurial/configitems.py	Fri Jun 30 03:32:09 2017 +0200
@@ -56,6 +56,9 @@
 
 coreconfigitem = getitemregister(coreitems)
 
+coreconfigitem('color', 'mode',
+    default='auto',
+)
 coreconfigitem('devel', 'all-warnings',
     default=False,
 )