mercurial/copies.py

--- a/mercurial/copies.py	Tue Apr 21 15:00:32 2020 +0200
+++ b/mercurial/copies.py	Fri Oct 02 15:41:31 2020 +0200
@@ -259,7 +259,7 @@
     children = {}
 
     cl = repo.changelog
-    isancestor = cached_is_ancestor(cl.isancestorrev)
+    isancestor = cl.isancestorrev
     missingrevs = cl.findmissingrevs(common=[a.rev()], heads=[b.rev()])
     mrset = set(missingrevs)
     roots = set()
@@ -321,6 +321,8 @@
             list(revs), children, targetrev, revinfo, isancestor
         )
 
+    isancestor = cached_is_ancestor(isancestor)
+
     all_copies = {}
     for r in revs:
         copies = all_copies.pop(r, None)