--- a/mercurial/copies.py	Wed Oct 02 17:42:01 2019 -0400
+++ b/mercurial/copies.py	Tue Oct 15 18:42:03 2019 +0200
@@ -204,7 +204,7 @@
     if a.rev() in (node.nullrev, b.rev()):
         return {}
 
-    repo = a.repo()
+    repo = a.repo().unfiltered()
     children = {}
     revinfo = _revinfogetter(repo)