Fix typo in bugzilla extension.

hgext/bugzilla.py

@@ -300,7 +300,7 b' def hook(ui, repo, hooktype, node=None, '
                          hooktype)
     try:
         bz = bugzilla(ui, repo)
-        ctx = repo.changctx(node)
+        ctx = repo.changectx(node)
         ids = bz.find_bug_ids(ctx)
         if ids:
             for id in ids: