diff -r e061a1df32a8 -r 473abf4728bf mercurial/configitems.py
--- a/mercurial/configitems.py	Thu Apr 08 14:58:44 2021 +0200
+++ b/mercurial/configitems.py	Tue Mar 30 09:56:04 2021 +0200
@@ -959,6 +959,11 @@
 )
 coreconfigitem(
     b'experimental',
+    b'dirstate-tree.in-memory',
+    default=False,
+)
+coreconfigitem(
+    b'experimental',
     b'editortmpinhg',
     default=False,
 )