ENH: CI: Add a `[skip cirrus]` markup to skip running Cirrus jobs.

It would be nice to be able to skip the Cirrus jobs, especially in their current state. It looks like it might be as simple as adding something like

    if "[skip cirrus]" in dct["message"]:
        return []

at the appropriate place in .cirrus.star, but that idea is the result of about 5 minutes of code browsing. @andyfaff, would something like that work?

[andyfaff]

CIRRUS_CHANGE_IN_REPO is the SHA of the last commit. The code I mentioned above grabs information from GH on that commit message, placing it into dct. One of the keys is message which is the commit message.

[andyfaff]

It’s inbuilt to cirrus-ci. See https://github.com/andyfaff/scipy/pull/36/checks?check_run_id=8970766219 where I created a PR against my own fork with [skip cirrus] in the commit message. The CI run is skipped automatically without having to change any of our configuration.

Your suggestion would also work @WarrenWeckesser. Note however, that there’s nothing wrong with the infrastructure of the cirrus_general_ci runs, there are 15 failing tests that we need to address.