diff -r bd725a71f274 -r 1a314176da9c mercurial/configitems.py
--- a/mercurial/configitems.py	Mon Nov 06 14:56:17 2017 -0500
+++ b/mercurial/configitems.py	Mon Nov 06 22:32:41 2017 -0800
@@ -814,6 +814,15 @@
 coreconfigitem('subrepos', 'allowed',
     default=dynamicdefault,  # to make backporting simpler
 )
+coreconfigitem('subrepos', 'hg:allowed',
+    default=dynamicdefault,
+)
+coreconfigitem('subrepos', 'git:allowed',
+    default=dynamicdefault,
+)
+coreconfigitem('subrepos', 'svn:allowed',
+    default=dynamicdefault,
+)
 coreconfigitem('templates', '.*',
     default=None,
     generic=True,