VCS links

[jayvdb]

VCS links like git+https://github.com/foo/bar, git+https://github.com/foo/bar#egg=baz and git+https://github.com/foo/bar#egg=baz-1.0 are not supported. Similar to #120

They are supported by pip and setuptools.

 >>> packaging.requirements.Requirement('git+https://github.com/foo/bar')
  Traceback (most recent call last):
  File "packaging/requirements.py", line 97, in __init__
    requirement_string[e.loc:e.loc + 8]))
packaging.requirements.InvalidRequirement: Invalid requirement, parse error at "'+https:/'"

[xavfernandez]

packaging implements PEP508.

You should be using baz @ git+https://github.com/foo/bar form.