Fix misused variable that was preventing permutations of classes from being tested (GH-93935)

Author: LostBenjamin

Lib/test/test_functools.py

@@ -2003,7 +2003,7 @@ class D(collections.defaultdict):
         c.MutableSequence.register(D)
         bases = [c.MutableSequence, c.MutableMapping]
         for haystack in permutations(bases):
-            m = mro(D, bases)
+            m = mro(D, haystack)
             self.assertEqual(m, [D, c.MutableSequence, c.Sequence, c.Reversible,
                                  collections.defaultdict, dict, c.MutableMapping, c.Mapping,
                                  c.Collection, c.Sized, c.Iterable, c.Container,