The commit message is also wrong.

Sorry, I’m away from my PC and cannot update the message. Feel free to push over or merge as is (after all, the commit id is from the backport, so it’s only half off).

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 7c6d9ebd1400434a4d67143ff4bf682677ca7e2e

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

$ git commit -am 'Backport PR #21361: Fix flake8 from #21335'

4. Push to a named branch :

git push YOURFORK v3.5.x:auto-backport-of-pr-21361-on-v3.5.x

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

"Backport PR #21361 on branch v3.5.x (Fix flake8 from #21335)"

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!

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

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

I'll just throw the fix into the existing backport in #21360.