Fix test.

dulwich/tests/test_object_store.py

@@ -24,7 +24,7 @@ class ObjectStoreTests(TestCase):
 
     def test_pack_dir(self):
         o = ObjectStore("foo")
-        self.assertEquals("foo/pack", o.pack_dir())
+        self.assertEquals("foo/pack", o.pack_dir)
 
     def test_empty_packs(self):
         o = ObjectStore("foo")