urlsafe_base64_encode broken on Django 2.0

[Nick]

Suppose we have:

hashed_msg = hmac.new(key, msg=message, digestmod=sha384)
url = urlsafe_base64_encode(hashed.digest())

Now url is a bytes object, say b'asdfwerqwefa'. In django 1.11, bytes-like objects could be placed in urls no problem, creating (say) localhost:8000/asdfwerqwefa

However, in django 2.0, the url becomes (say)

localhost:8000/b'asdfwerqwefa'

which seems less 'urlsafe', as the quotes and the 'b' are added into the url. Shouldn't urlsafe_base64_encode now return a string, if bytes in urls now retain the quotes?