I modified the patch to handle the last case using your way as well.

Anyway, I found out that urlsplit and urlparse got the same issue as well.

>>> urlparse('python.org', b'http://')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/sky/Code/python/programming_language/cpython/Lib/urllib/parse.py", line 292, in urlparse
    url, scheme, _coerce_result = _coerce_args(url, scheme)
  File "/home/sky/Code/python/programming_language/cpython/Lib/urllib/parse.py", line 109, in _coerce_args
    raise TypeError("Cannot mix str and non-str arguments")
TypeError: Cannot mix str and non-str arguments
>>> urlparse('python.org', b'')
ParseResult(scheme=b'', netloc='', path='python.org', params='', query='', fragment='')
>>> urlparse('python.org', 0)
ParseResult(scheme=0, netloc='', path='python.org', params='', query='', fragment='')

Same thing happens in urlsplit. Fortunately, urlunsplit and urlunparse don't have this issue.