diff -r d5362671993b -r 23783463d720 mercurial/configitems.py
--- a/mercurial/configitems.py	Sun Oct 08 22:06:35 2017 +0200
+++ b/mercurial/configitems.py	Sun Oct 08 22:07:21 2017 +0200
@@ -275,6 +275,9 @@
 coreconfigitem('experimental', 'graphstyle.parent',
     default=dynamicdefault,
 )
+coreconfigitem('experimental', 'graphstyle.missing',
+    default=dynamicdefault,
+)
 coreconfigitem('experimental', 'hook-track-tags',
     default=False,
 )