[FIX]message_auto_subscribe getting polluted value

```
        # auto_subscribe: take values and defaults into account
        create_values = dict(values)
        for key, val in context.iteritems():
            if key.startswith('default_'):
                create_values[key[8:]] = val
```
I guess the above code is there for passing the test, but in result it is there to pollute user created value