diff -r 4450faeb52bb -r 2ab79873786e mercurial/configitems.py
--- a/mercurial/configitems.py	Fri Apr 15 22:02:07 2022 +0200
+++ b/mercurial/configitems.py	Tue Apr 05 05:19:47 2022 +0200
@@ -1386,6 +1386,12 @@
 )
 coreconfigitem(
     b'format',
+    b'use-share-safe.automatic-upgrade-of-mismatching-repositories',
+    default=False,
+    experimental=True,
+)
+coreconfigitem(
+    b'format',
     b'internal-phase',
     default=False,
     experimental=True,