Env proxy parser error

[aetherwu]

set http_proxy=http://127.0.0.1:7890 & set https_proxy=https://127.0.0.1:7890
Went wrong around _models.py:

if not self.host:
                raise InvalidURL("No host included in URL.")

Where as
set http_proxy=http://127.0.0.1:7890
Works fine.

I am sorry that I couldn't provide a PR but I hope this issue helps.

[lovelydinosaur]

Could you start by providing us with a traceback.
I can't find the line you're referring too.