--- a/tests/test-check-interfaces.py	Thu Feb 18 18:18:35 2021 +0100
+++ b/tests/test-check-interfaces.py	Fri Feb 19 10:53:27 2021 +0100
@@ -85,6 +85,7 @@
 class dummyrepo(object):
     def __init__(self):
         self.ui = uimod.ui()
+        self._wanted_sidedata = set()
 
     def filtered(self, name):
         pass