--- a/hgext/inhibit.py	Mon Apr 06 11:21:20 2015 -0700
+++ b/hgext/inhibit.py	Fri Apr 10 23:16:10 2015 -0400
@@ -235,7 +235,7 @@
     # We extract the symbols that look like hashes and add them to the
     # explicitaccess set
     orig(tree, repo)
-    if repo and repo.filtername == 'visible':
+    if repo is not None and repo.filtername == 'visible':
         prelength = len(repo._explicitaccess)
         repo.symbols = gethashsymbols(tree)
         cl = repo.unfiltered().changelog