refleak in twisted.test.test_pb.BrokerTestCase.test_publishable

[catlee]

As demonstrated in this patch, test_publishable leaks [<twisted.test.test_pb.DumbPub instance at 0x2111200>, <twisted.spread.pb.RemoteReference instance at 0x21115f0>] when run. Possibly an indication of an underlying reference leak?

twisted/test/test_pb.py

@@ -723 +723 @@
         self.assertIdentical(vcc.observer, None, "observer was not removed")
 
     def test_publishable(self):
+        gc.collect()
+        old_garbage = len(gc.garbage)
         try:
             os.unlink('None-None-TESTING.pub') # from RemotePublished.getFileName
         except OSError:
@@ -750 +752 @@
         # timestamp's clean, our cache file is up-to-date
         self.assertEquals(obj._wasCleanWhenLoaded, 1)
 
+        gc.collect()
+        self.assertEquals(len(gc.garbage), old_garbage, "Uncollectable garbage: %s" % gc.garbage)
+
     def gotCopy(self, val):
         self.thunkResult = val.id