diff -r b7a75b9a3386 -r 0407a51b9d8c mercurial/subrepo.py
--- a/mercurial/subrepo.py	Tue Jul 11 08:52:55 2017 -0700
+++ b/mercurial/subrepo.py	Fri Jul 14 14:22:40 2017 -0700
@@ -401,7 +401,7 @@
     substate = getattr(ctx, "substate", None)
     if not substate:
         return commitphase
-    check = ui.config('phases', 'checksubrepos', 'follow')
+    check = ui.config('phases', 'checksubrepos')
     if check not in ('ignore', 'follow', 'abort'):
         raise error.Abort(_('invalid phases.checksubrepos configuration: %s')
                          % (check))