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 v3.1.x
$ git pull

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

$ git cherry-pick -m1 9faf2313cf0e37a6b01ad691b8a430eb2b4ebe3f

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

$ git commit -am 'Backport PR #13710: TST: only test agg_filter extensions with baseline images'

4. Push to a named branch :

git push YOURFORK v3.1.x:auto-backport-of-pr-13710-on-v3.1.x

5. Create a PR against branch v3.1.x, I would have named this PR:

"Backport PR #13710 on branch v3.1.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.

backport merged as part of #13704