--- a/mercurial/upgrade_utils/actions.py	Wed Apr 07 00:12:07 2021 +0200
+++ b/mercurial/upgrade_utils/actions.py	Wed Apr 07 12:15:28 2021 +0200
@@ -428,7 +428,9 @@
         # return the first valid value as the selection code would do
         for comp in compengines:
             if comp in util.compengines:
-                return comp
+                e = util.compengines[comp]
+                if e.available() and e.revlogheader():
+                    return comp
 
         # no valide compression found lets display it all for clarity
         return b','.join(compengines)