Enforce backport conditions on v*-doc branches

[QuLogic]

PR Summary

The v*-doc backport branches build docs against the released version. This is not enforced in the CI, and PRs can be backported that have no effect (e.e.g, #21631).

This PR adds a check that lib files are not modified on backports, and also attempts to run CircleCI with the right version.

Also fixes the added-and-modified check which was incorrectly failing in #21799, as noted on gitter.

PR Checklist

Tests and Styling

• [n/a] Has pytest style unit tests (and pytest passes).
• Is Flake 8 compliant (install flake8-docstrings and run flake8 --docstring-convention=all).

Documentation

• [n/a] New features are documented, with examples if plot related.
• [n/a] New features have an entry in doc/users/next_whats_new/ (follow instructions in README.rst there).
• [n/a] API changes documented in doc/api/next_api_changes/ (follow instructions in README.rst there).
• Documentation is sphinx and numpydoc compliant (the docs should build without error).

[QuLogic]

I'll try to post a test PR for this before it gets merged.

[QuLogic]

Here is a build on v3.5.0-doc showing that we are building against the release for the backport doc build.

Here is a pull request with an invalid backport.

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout v3.5.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -m1 6cebe46157976ab16cc8da38415e5fb15bcc4607

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #21833: Enforce backport conditions on v*-doc branches'

4. Push to a named branch:

git push YOURFORK v3.5.x:auto-backport-of-pr-21833-on-v3.5.x

5. Create a PR against branch v3.5.x, I would have named this PR:

"Backport PR #21833 on branch v3.5.x (Enforce backport conditions on v*-doc branches)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout v3.5.1-doc
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -m1 6cebe46157976ab16cc8da38415e5fb15bcc4607

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #21833: Enforce backport conditions on v*-doc branches'

4. Push to a named branch:

git push YOURFORK v3.5.1-doc:auto-backport-of-pr-21833-on-v3.5.1-doc

5. Create a PR against branch v3.5.1-doc, I would have named this PR:

"Backport PR #21833 on branch v3.5.1-doc (Enforce backport conditions on v*-doc branches)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.