--- a/mercurial/configitems.py	Mon Jun 04 12:12:00 2018 +0200
+++ b/mercurial/configitems.py	Mon Jun 04 22:23:18 2018 +0200
@@ -652,6 +652,9 @@
 coreconfigitem('format', 'obsstore-version',
     default=None,
 )
+coreconfigitem('format', 'sparse-revlog',
+    default=False,
+)
 coreconfigitem('format', 'usefncache',
     default=True,
 )