Amend upstream-dev GitHub action + Bug fixes

[andersy005]

• Closes failing nightly CI #4603
• Closes mamba does not use strict channel priority (in our CI) #4643
• User visible changes (including notable bug fixes) are documented in whats-new.rst

[keewis]

looks good to me. I don't know enough about github actions to tell whether this actually works, though.

We might be able to avoid the extra step, but this comes at the cost of a slightly higher complexity (see below).

[keewis]

I looked over the workflow file and noticed a few more things I would change.

Also, we should probably refactor the parse script, I think being able to pass the files via command line helps a lot when testing the script locally. I added a modified version to my test project which parses the short test summary info lines (but feel free to edit it if you think something is hard to read or if it is too fragile). The call in the CI file would then have to be

shopt -s globstar
python .github/workflows/parse_logs.py logs/**/*-log

Edit: actually, let's make that a new PR

[andersy005]

@keewis,

When you get a chance, this is ready for another round of review...

[keewis]

thanks, @andersy005, looks good to me.

[mathause]

One more point - now the Actions also run on our personal forks. Is that something we want or should/ can this be disabled?

[keewis]

I don't think we should do that, running the same CI on the same code multiple times in parallel doesn't make much sense. We might be able to stop that by tweaking the on section, but I would fix that in a new PR.

[keewis]

alright then, let's merge on green.

This is also for a different PR, but maybe we can add a "import xarray" step. This is useful because in case some required dependencies are missing (like numpy, see #4640) we can skip running the tests: they would fail anyway.

[dcherian]

Thanks @andersy005 & @keewis !