Python 3.7.6 urllib.parse changes break gabbi tests

[cdent]

Python 3.7.6 was released with a change to how urllib.parse will deal with "localhost:80".

3.7.5:

>>> from urllib import parse
>>> parse.urlparse("foobar.com:999")
ParseResult(scheme='', netloc='', path='foobar.com:999', params='', query='', fragment='')

3.7.6

>>> from urllib import parse
>>> parse.urlparse("foobar.com:999")
ParseResult(scheme='foobar.com', netloc='', path='999', params='', query='', fragment='')

See this bug: https://bugs.python.org/issue27657 and a related pull request: python/cpython#16839

This breaks gabbi.utils:host_info_from_target. It also apparently break a whole ton of other software out there in the world. This a) seems like the wrong fix, b) if it is indeed correct, is bad for a minor release.

Since gabbi only talks http, it can probably be fixed by branch on whether the target starts with http but some discussion is probably worth having before going down that route.

[cdent]

This reactivated for python 3.9 so will need a real fix.