diff --git a/mercurial/copies.py b/mercurial/copies.py
index b8d60845fa5de2e098d31bca699618bf96c436e1_bWVyY3VyaWFsL2NvcGllcy5weQ==..00de32aa834e0df449f81deeef94337e12f5ef4f_bWVyY3VyaWFsL2NvcGllcy5weQ== 100644
--- a/mercurial/copies.py
+++ b/mercurial/copies.py
@@ -204,7 +204,7 @@
     if a.rev() in (node.nullrev, b.rev()):
         return {}
 
-    repo = a.repo()
+    repo = a.repo().unfiltered()
     children = {}
     revinfo = _revinfogetter(repo)