Revert unneeded changes to unit tests.

Author: nascheme

Lib/test/test_gc.py

@@ -1066,8 +1066,8 @@ class Z:
         # release references and create trash
         del a, wr_cycle
         gc.collect()
-        # In older versions of Python, the weakref was cleared by the
-        # gc.  Now it is not cleared and so the callback is run.
+        # if called, it means there is a bug in the GC.  The weakref should be
+        # cleared before Z dies.
         callback.assert_not_called()
         gc.enable()
 

Lib/test/test_weakref.py

@@ -1314,7 +1314,7 @@ def check_len_cycles(self, dict_type, cons):
         n2 = len(dct)
         # one item may be kept alive inside the iterator
         self.assertIn(n1, (0, 1))
-        self.assertIn(n2, (0, 1))
+        self.assertEqual(n2, 0)
 
     def test_weak_keyed_len_cycles(self):
         self.check_len_cycles(weakref.WeakKeyDictionary, lambda k: (k, 1))