`python-version` is ignored on MacOS runners

[christophfink]

Description:
Specifying a with: python-version works for Windows and Linux runners, but seemingly is ignored on MacOS runners, where setup-python resorts to the newest Python version available

Action version:
actions/setup-python@5

Platform:

• Ubuntu
• macOS
• Windows

Runner type:

• Hosted
• Self-hosted

Tools version:
n/a

Repro steps:
Run a GitHub workflow YAML file that specifies a python-version on MacOS runners. See below for an example YAML, and the following repo for a running example: https://github.com/christophfink/gh-actions-python-versions/actions/runs/10508872098

Expected behavior:
actions/setup-python installs the requested python version (as on Windows and Linux runners)

Actual behavior:
actions/setup-python installs the latest edit: default python version

[priya-kinthali]

Hello @christophfink 👋,
Thank you for reporting this. We will investigate the issue and get back to you as soon as we have updates.

[priya-kinthali]

Hello @christophfink 👋,

Thank you for raising this issue. It seems that the problem with the python-version being ignored on MacOS runners may be related to the shell configuration specified in your workflow which is shell: bash -l {0}.
To avoid this, it is recommended to use the shell configuration like : shell: bash.
For more details, please refer to the related discussion here: actions/setup-python#179 (comment).
I hope this helps!

[christophfink]

Hi @priya-kinthali !

Thanks for your quick help, this is, indeed, fixing the issue for me. The linked issue has a great explanation, thanks for that, too.