--- a/mercurial/unionrepo.py	Sat Dec 03 00:13:50 2022 +0100
+++ b/mercurial/unionrepo.py	Sat Dec 03 00:16:07 2022 +0100
@@ -257,8 +257,8 @@
     def cancopy(self):
         return False
 
-    def peer(self):
-        return unionpeer(self)
+    def peer(self, path=None):
+        return unionpeer(self, path=None)
 
     def getcwd(self):
         return encoding.getcwd()  # always outside the repo