tests: use interfaceutil in simplestorerepo

Without it, we crash at module import time.

This has likely been busted since 856f381ad74b.

Differential Revision: https://phab.mercurial-scm.org/D3884

tests/simplestorerepo.py

@@ -24,9 +24,6 b' from mercurial.node import ('
 from mercurial.thirdparty import (
     cbor,
 )
-from mercurial.thirdparty.zope import (
-    interface as zi,
-)
 from mercurial import (
     ancestor,
     bundlerepo,
@@ -40,6 +37,9 b' from mercurial import ('
     store,
     verify,
 )
+from mercurial.utils import (
+    interfaceutil,
+)
 
 # Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
 # extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
@@ -60,7 +60,7 b' def validaterev(rev):'
     if not isinstance(rev, int):
         raise ValueError('expected int')
 
[e-mail](repository.ifilestorage)
[e-mail](repository.ifilestorage)
 class filestorage(object):
     """Implements storage for a tracked path.