diff -r 582676acaf6d -r dbcb466d0065 mercurial/configitems.py
--- a/mercurial/configitems.py	Thu Sep 27 09:23:17 2018 -0700
+++ b/mercurial/configitems.py	Fri Sep 28 09:46:50 2018 -0700
@@ -941,6 +941,9 @@
 coreconfigitem('push', 'pushvars.server',
     default=False,
 )
+coreconfigitem('storage', 'new-repo-backend',
+    default='revlogv1',
+)
 coreconfigitem('storage', 'revlog.optimize-delta-parent-choice',
     default=True,
     alias=[('format', 'aggressivemergedeltas')],