.gitignore

*.egg*
/.tox

demo.sh

#!/bin/sh
set -ex
rm -rf .tox
tox  # once to create the virtualenv
tmp="${TMPDIR:-/tmp}/pip-*"
ls -lartd ${tmp}  # see what's there already
tox  # now run tox for real
ls -lartd ${tmp}  # should see a new, empty directory listed
.tox/py27/bin/pip install -U git+https://github.com/habnabit/pip@fix-no-clean
tox  # run tox with the fix
ls -lartd ${tmp}  # should see a new, not-empty directory listed

pip_2689_test.py

installed = True

setup.py

from setuptools import setup


setup(
    name='pip-2689-test',
    version='1.2.3',
    py_modules=['pip_2689_test'],
)

tox.ini

[tox]
envlist = py27

[testenv]
install_command = pip install --no-clean {opts} {packages}