[Distutils] Virtalenv and setuptools [was: latest setuptools appears to require six in a breaking way]

[Paul Moore]

On 25 January 2017 at 17:20, Chris Withers <chris at simplistix.co.uk> wrote:
> Right, so what's the recommended one-step way to set up a virtualenv now in
> Py 2.6-3.6?

This is the point I would consider most significant here. Virtualenv
is deliberately built to allow use offline - pip, wheel and setuptools
are bundled so that it's possible to create a virtualenv without
needing Internet access. This change to setuptools will, if I
understand it, break that expectation.

While it's not a common scenario, I think it's something that should
be considered. Going forward, I see a number of options for
virtualenv:

1. Bundle all of setuptools' dependencies as well.
2. Drop the "no internet required" constraint - if we do this, it may
be reasonable to only bundle pip, and get latest versions of
everything else from PyPI.
3. Drop auto-installing setuptools (it's not needed unless you're
installing from sdist, and it's only a "pip install setuptools" away
for people who need it).
4. Document the changed behaviour by saying that no internet is
required as long as you use --no-setuptools.

Thoughts, anyone? Is the situation common enough to warrant anything
other than (4)? It used to be for me, when pip didn't cache downloads
and I had a secured proxy to deal with, but now I'd be OK with (4).

Paul