Installing six<1.10 breaks fresh virtualenv

[asottile]

I wasn't sure which project to make this ticket on since it involves a combination of pip / setuptools / virtualenv to reproduce.

A downgrading of six in a fresh virtualenv makes it impossible to install packages from source.

First create a fresh virtualenv (I'm using 15.0.1):

virtualenv venv

This goes out to pypi and downloads the latest versions of pip / setuptools / wheel / etc. In this case bringing in the new setuptools==34.x

$ pip freeze --all
appdirs==1.4.0
packaging==16.8
pip==9.0.1
pkg-resources==0.0.0
pyparsing==2.1.10
setuptools==34.0.2
six==1.10.0
wheel==0.30.0a0

Next, downgrade six in this virtualenv

$ pip install six==1.9
Collecting six==1.9
  Using cached six-1.9.0-py2.py3-none-any.whl
Installing collected packages: six
  Found existing installation: six 1.10.0
    Uninstalling six-1.10.0:
      Successfully uninstalled six-1.10.0
Successfully installed six-1.9.0

Now pip cannot install from source distributions:

$ pip install simplejson
Collecting simplejson
  Using cached simplejson-3.10.0.tar.gz
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/nail/tmp/pip-build-vtpFz7/simplejson/setup.py", line 111, in <module>
        run_setup(not IS_PYPY)
      File "/nail/tmp/pip-build-vtpFz7/simplejson/setup.py", line 108, in run_setup
        **kw)
      File "/usr/lib/python2.7/distutils/core.py", line 111, in setup
        _setup_distribution = dist = klass(attrs)
      File "/tmp/venv/local/lib/python2.7/site-packages/setuptools/dist.py", line 320, in __init__
        _Distribution.__init__(self, attrs)
      File "/usr/lib/python2.7/distutils/dist.py", line 287, in __init__
        self.finalize_options()
      File "/tmp/venv/local/lib/python2.7/site-packages/setuptools/dist.py", line 386, in finalize_options
        ep.require(installer=self.fetch_build_egg)
      File "/tmp/venv/local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 2245, in require
        items = working_set.resolve(reqs, env, installer)
      File "/tmp/venv/local/lib/python2.7/site-packages/pkg_resources/__init__.py", line 834, in resolve
        raise VersionConflict(dist, req).with_context(dependent_req)
    pkg_resources.VersionConflict: (six 1.9.0 (/tmp/venv/lib/python2.7/site-packages), Requirement.parse('six>=1.10.0'))
    
    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /nail/tmp/pip-build-vtpFz7/simplejson/

Although this bug report seems a little contrived, it's the simplest case. This is breaking actual builds with much more complicated setups.

A "fix" to escape the breaking is to either downgrade setuptools or restore the version of six again (luckily six provides a wheel!).

[truthdoug]

There was a recent commit to setuptools which requires >=1.10.0 (line 167). This was part of the 34.0.2 release which came out just two days ago.

[truthdoug]

(minor correction: the first release with this change was 34.0.0 (released on Jan 23))

[asottile]

This is no longer an issue after setuptools re-vendored dependencies -- closing.