1. It actually uses `force_bytes`, which in fact is a lot better (`smart_bytes` does unnecessary check for type of the input parameter, thus is harder to understand why it's used here)
2. We know the input, we know this should not be unicode, that's why we can simply `encode` this. Using `django.utils` is not needed here imho and could fail in future (if at some point Django devs would change it's behaviour, however not probable it sounds currently).

I'm not forcing this, it was simply not obvious for me during review why this particular function was used here. Thought it might not be obvious to someone else too.