message: Fix python 3 test failure due to string vs byte (b'')
diff: @@ -131,7 +131,7 @@ class SparseOpsTest(test_util.TensorFlowTestCase, parameterized.TestCase):
  values=['a', 'b'],
  dense_shape=[2, 3])
  dense = sparse_ops.sparse_tensor_to_dense(sp)
  - expected_dense = [['a', '', ''], ['', '', 'b']]
  + expected_dense = [[b'a', b'', b''], [b'', b'', b'b']]
  result_dense = self.evaluate(dense)
  self.assertAllEqual(expected_dense, result_dense)
  