diff -r c0c6df81c9bb -r dd11df900f7f mercurial/configitems.py
--- a/mercurial/configitems.py	Mon Dec 11 09:37:11 2017 -0500
+++ b/mercurial/configitems.py	Mon Dec 11 22:16:13 2017 -0800
@@ -1269,3 +1269,6 @@
 coreconfigitem('rebase', 'singletransaction',
     default=False,
 )
+coreconfigitem('rebase', 'experimental.inmemory',
+    default=False,
+)