message: TF 1.15 compatibility fix
  This PR fixes a failed tests that works in 2.0 but failed in 0.8.
  Once this PR is merged, R0.8 branch will be rebased.
diff: @@ -55,7 +55,7 @@ def test_tiff_io_tensor():
  tiff = tfio.IOTensor.from_tiff(filename)
  assert tiff.keys == list(range(5))
  for i in tiff.keys:
  - assert np.all(images[i] == tiff(i).to_tensor())
  + assert np.all(images[i].numpy() == tiff(i).to_tensor().numpy())
  if __name__ == "__main__":
  