Upgrade to 20.2 fails on Windows Server 2019

[pmeier]

Environment

• pip version: 20.2
• Python version: 3.[6-8]
• OS: Windows Server 2019 via GitHubActions

Description

pip upgrade to 20.2 fails for Windows Server 2019. I've created a sample repository that runs pip install --upgrade with "pip==20.1.1" (old) and "pip==20.2" against all major platforms and Python 3.[6-8].

Note, that this is not a sudo issue, since the upgrade to the previous version runs fine.

Expected behavior

Upgrade without failures.

How to Reproduce

pip install --upgrade "pip==20.2"

Output

ERROR: Could not install packages due to an EnvironmentError: [WinError 5] Access is denied: 'C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\pip-uninstall-q3fbhmha\\pip.exe'
Consider using the `--user` option or check the permissions.

[uranusjr]

Use python -m pip instead. (I thought we fixed this error message a while ago?)

[pfmoore]

Use python -m pip instead.

Or if you're not running in a virtualenv, use py -m pip. (Actually py -m pip works in a virtualenv too, so maybe use that regardless?)

[uranusjr]

I wonder if py.exe is available in the GitHub Actions’ Windows container (definitely use it if it is).

[pmeier]

python -m pip does the trick. Is this a general recommendation when upgrading pip?

I wonder if py.exe is available in the GitHub Actions’ Windows container (definitely use it if it is).

I'd rather not, since this then requires different code for Windows.

[uranusjr]

Yes, -m pip is the generally preferred way to run pip. There are even talks to deprecate the pip command entirely, but that’d be a very long term project.

[pmeier]

@uranusjr Should I close this or do you want to keep it open?

[pradyunsg]

(I thought we fixed this error message a while ago?)

Can someone with Windows test this, and check if the check in the logic for "modifying pip" is correct?

[pfmoore]

I'm not entirely sure what you want testing? The "pip is outdated" message correctly suggests python -m pip (using the full path to sys.executable). The Access Denied error, as quoted by the OP, isn't specific to upgrading pip and doesn't mention how to invoke pip at all.

[uranusjr]

I believe there’s logic somewhere that tries to detect a user wants to do pip install -U pip and shows a different error message. That message should have been triggered here, but is not according to this report.

[uranusjr]

Reading the implementation, the check (pip._internal.utils.misc.protect_pip_from_modification_on_windows) only guards against running through pip.exe (and the versioned variants), not pip without the extension. git blame led me to #7358, which removed the guard against the extension-less pip command since it mis-identifies python path\to\repo\src\pip as an error. The consensus seems to be that it is not worth the effort to improve the identification logic (my #7558 was closed unmerged), and pip should find a way to make this .exe replacement work, or deprecate the entry points altogether. So I’m closing this since the problem is tracked in #7567.