[Distutils] Use of direct references in requirements for setuptools

[Steve Kowalik]

Hi,

Currently, pip supports use of direct references[1][2] in requirement
files, which means it includes code that will deal with downloading
files over HTTP, or git, etc.

setuptools does not have this support, and in order for setuptools to
completely implement PEP 508 support, we should come up with a plan
what to do when setuptools encounters a requirement that uses a direct
reference.

The options that I can see are:
1) When egg_info is run, exit with an error saying "Please don't do
that"
2) Warn about the requirement, and that we will just depend on it, but
drop the direct reference.
3) Add support to setuptools. Personally, I don't like this plan, but
perhaps it's easy.


1: For example: testtools@ https://github.com/testing-cabal/testtools
2: It doesn't yet support the format specified by PEP 508, but the
functionality exists and works.

-- 
                                         Steve
Oh, in case you got covered in that Repulsion Gel, here's some advice
the lab boys gave me: [paper rustling] DO NOT get covered in the
Repulsion Gel.
          - Cave Johnson, CEO of Aperture Science