Error in tokenize with specific combination of keytokens

The following test fails:

``` python
def test_error(self):
        tokenize('Decretos-Lei n.os 29/2000', {'Decretos-Leis', ' ',
                                               'n.os', 'Decreto', 'Lei',
                                               'Lei Orgânica'})
```

with an error coming from the C++ code.
