ensurepip optionally installs or upgrades 'pip' and 'setuptools' using
the version of those modules bundled with Python. The internal PIP
installation routine by default temporarily uses its cache, if it
exists. This is undesirable as Python builds and installations may be
independent of the user running the build, whilst PIP cache location
is dependent on the user's environment and outside of the build
environment.
At the same time, there's no value in using the cache while installing
bundled modules.
This change disables PIP caching when used in ensurepip.
Ensure that the uninstall helper for Windows passes the proper
flags to pip to prevent it from checking PyPI if the pip that
we're currently attempting to uninstall is the latest verison.
I have compared output between pre- and post-patch runs of these tests
to make sure there's nothing missing and nothing broken, on both
Windows and Linux. The only differences I found were actually tests
that were previously *not* run.
The 3.4rc2 Windows uninstaller would fail if pip had been updated
to a version that didn't match the version installed by ensurepip.
This skip is no longer treated as an error, so an updated pip ends
up being handled like any other pip installed package and is left
alone by the CPython uninstaller.
ensurepip now sets PIP_CONFIG_FILE to os.devnull before
import pip from the wheel file. This also ensures venv
ignores the default settings when bootstrapping pip.
MvL would like to be able to preserve CPython's existing clean
uninstall behaviour on Windows before enabling the pip
installation option by default.
This private CLI means running "python -m ensurepip._uninstall"
will remove pip and setuptools before proceeding with the rest
of the uninstallation process.
If the version of pip differs from the one bootstrapped by
CPython, then the uninstallation helper will leave it alone
(just like any other pip installed packages)
Krzysztof Konopko
Igor Filatov
Donald Stufft
Zachary Ware
Benjamin Peterson
Nick Coghlan