--- a/mercurial/configitems.py	Wed Oct 31 11:02:08 2018 +0100
+++ b/mercurial/configitems.py	Wed Oct 31 15:27:06 2018 +0300
@@ -610,7 +610,7 @@
 coreconfigitem('experimental', 'server.manifestdata.recommended-batch-size',
     default=100000,
 )
-coreconfigitem('experimental.server', 'stream-narrow-clones',
+coreconfigitem('experimental', 'server.stream-narrow-clones',
     default=False,
 )
 coreconfigitem('experimental', 'single-head-per-branch',