message: Convert string to binary strings to clear python3 failures.
diff: @@ -237,9 +237,9 @@ class PrefetchingKernelsOpsTest(test.TestCase):
  buffer_resource_handle, ignore_lookup_error=True)
  with self.test_session() as sess:
  - self.assertEqual(["a"], sess.run(prefetch_op))
  - self.assertEqual(["b"], sess.run(prefetch_op))
  - self.assertEqual(["c"], sess.run(prefetch_op))
  + self.assertEqual([b"a"], sess.run(prefetch_op))
  + self.assertEqual([b"b"], sess.run(prefetch_op))
  + self.assertEqual([b"c"], sess.run(prefetch_op))
  with self.assertRaises(errors.OutOfRangeError):
  sess.run(prefetch_op)
  