message: Make batch_sequences_with_states_test.py work with the C API enabled.
  The C API improves static shape inference, making more errors caught
  at graph construction time instead of runtime.
diff: @@ -526,6 +526,11 @@ class PaddingTest(test.TestCase):
  "key_2": constant_op.constant([1.5, 2.5]) # length 2
  }
  + if ops._USE_C_API:
  + with self.assertRaisesRegexp(
  + ValueError, "Fill dimensions must be >= 0"):
  + _, padded_seq = sqss._padding(sequences, 2)
  + else:
  _, padded_seq = sqss._padding(sequences, 2)
  with self.assertRaisesOpError(
  ".*All sequence lengths must match, but received lengths.*"):
  