`TestMarian_MT_EN::test_batch_generation_mt_en` Failing due to randomly generated tokens

The test fails with the following:

```
_________________ TestMarian_MT_EN.test_batch_generation_mt_en _________________
[gw0] linux -- Python 3.6.9 /usr/local/bin/python

self =

@slow
def test_batch_generation_mt_en(self):
> self._assert_generated_batch_equal_expected()

tests/test_modeling_tf_marian.py:390:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
tests/test_modeling_tf_marian.py:366: in _assert_generated_batch_equal_expected
self.assertListEqual(self.expected_text, generated_words)
E AssertionError: Lists differ: ['Tou[19 chars] healed a man who was affected by the sad disease of leprosy.'] != ['Tou[19 chars] healed a man who was affected by▁kifkażUnjonik ill.']
E
E First differing element 0:
E 'Touc[17 chars]s healed a man who was affected by the sad disease of leprosy.'
E 'Touc[17 chars]s healed a man who was affected by▁kifkażUnjonik ill.'
E
E - ['Touching gently, Jesus healed a man who was affected by the sad disease of '
E ? ^^^^^^ ^^^ ^^^^^^^^^
E
E + ['Touching gently, Jesus healed a man who was affected by▁kifkażUnjonik ill.']
E ? ^^^^^ ^^^^^^ ^^^^^^ +
E
E - 'leprosy.']
```