message: Replace == with is in test comparing variable identity.
diff: @@ -235,8 +235,8 @@ class WrapFunctionTest(test.TestCase):
  self.assertIs(g_var_collection[0], v3_holder[0])
  # Both have only one value, and their values aren't equal. So no sharing.
  - self.assertNotEqual(g_wrapped.graph.get_collection(ops.GraphKeys.LOSSES),
  - f_wrapped.graph.get_collection(ops.GraphKeys.LOSSES))
  + self.assertIsNot(g_wrapped.graph.get_collection(ops.GraphKeys.LOSSES[0]),
  + f_wrapped.graph.get_collection(ops.GraphKeys.LOSSES)[0])
  def testGradientsOfPrune(self):
  