Pin pytest<4.1 to unbreak CI tests

[timhoffm]

PR Summary

Temporary fix for #13121.

This can be undone once a new pytest-cov release is out.

[jklymak]

Though should it just be !=4.1 ?

[hugovk]

Pytest > 4.1 will still have the same feature removed, so I think < 4.1 makes more sense until there's a new pytest-cov release.

[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 v3.0.x
$ git pull

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

$ git cherry-pick -m1 e6733748a5fd5b8081ff518aa64d50aac70ff1d4

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

$ git commit -am 'Backport PR #13122: Pin pytest<4.1 to unbreak CI tests'

4. Push to a named branch :

git push YOURFORK v3.0.x:auto-backport-of-pr-13122-on-v3.0.x

5. Create a PR against branch v3.0.x, I would have named this PR:

"Backport PR #13122 on branch v3.0.x"

And apply the correct labels and milestones.

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

If these instruction 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 v3.0.2-doc
$ git pull

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

$ git cherry-pick -m1 e6733748a5fd5b8081ff518aa64d50aac70ff1d4

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

$ git commit -am 'Backport PR #13122: Pin pytest<4.1 to unbreak CI tests'

4. Push to a named branch :

git push YOURFORK v3.0.2-doc:auto-backport-of-pr-13122-on-v3.0.2-doc

5. Create a PR against branch v3.0.2-doc, I would have named this PR:

"Backport PR #13122 on branch v3.0.2-doc"

And apply the correct labels and milestones.

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

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

[tacaswell]

ouch, does not backport to either branch cleanly :(

[timhoffm]

I hope that there will be a pytest-cov release soon since it's affecting all pojects using pytest-cov. This question is raised here pytest-dev/pytest-cov#253.

Therefore, I would wait for an answer of the pytest-cov developers before pinning and later unpinning the other branches manually.

[tacaswell]

@timhoffm fair enough.

[timhoffm]

pytest-cov 2.6.1 has just been released. So no need to backport anymore.