mercurial/bundle2.py

--- a/mercurial/bundle2.py	Fri Jun 16 22:57:31 2017 -0700
+++ b/mercurial/bundle2.py	Sun May 28 00:12:38 2017 +0200
@@ -1323,7 +1323,8 @@
         caps['obsmarkers'] = supportedformat
     if allowpushback:
         caps['pushback'] = ()
-    if not repo.ui.configbool('experimental', 'checkheads-strict', True):
+    cpmode = repo.ui.config('server', 'concurrent-push-mode', 'strict')
+    if cpmode == 'check-related':
         caps['checkheads'] = ('related',)
     return caps