message: Remove ops.device(None).__enter__ from eager:core_test.
  Those statements are not necessary for the test to consistently pass.
diff: @@ -79,7 +79,6 @@ class TFETest(test_util.TensorFlowTestCase):
  def setUp(self):
  super(TFETest, self).setUp()
  - ops.device(None).__enter__()
  context._reset_context()
  configure_virtual_cpus()
  @@ -1064,7 +1063,6 @@ class SendRecvTest(test_util.TensorFlowTestCase):
  def setUp(self):
  super(SendRecvTest, self).setUp()
  - ops.device(None).__enter__()
  context._reset_context()
  configure_virtual_cpus()
  @@ -1101,7 +1099,6 @@ class EagerTensorCacheTest(test_util.TensorFlowTestCase):
  def setUp(self):
  super(EagerTensorCacheTest, self).setUp()
  - ops.device(None).__enter__()
  context._reset_context()
  configure_virtual_cpus()
  