diff -r cb516a854bc7 -r af62936c2508 mercurial/configitems.py
--- a/mercurial/configitems.py	Wed Oct 10 17:36:59 2018 +0300
+++ b/mercurial/configitems.py	Wed Sep 26 17:20:04 2018 +0300
@@ -610,6 +610,9 @@
 coreconfigitem('experimental', 'server.manifestdata.recommended-batch-size',
     default=100000,
 )
+coreconfigitem('experimental.server', 'stream-narrow-clones',
+    default=False,
+)
 coreconfigitem('experimental', 'single-head-per-branch',
     default=False,
 )