The PR #17170 broke buildbot https://buildbot.python.org/all/#/builders/40/builds/3413 and it was merged whereas the CLA was not signed.

So that means you'd rather I open a completely new pull request with the buildbot failure fixed, instead of a fix on top of current master?

@vstinner: Please replace # with GH- in the commit message next time. Thanks!

So that means you'd rather I open a completely new pull request with the buildbot failure fixed, instead of a fix on top of current master?

First of all, please sign the CLA: see the bot's explanation.
#17170 (comment)

I merged my revert, so in short you have to rewrite PR #17170. If possible, with a fix for the Windows 7 buildbot. By default, if a change breaks a buildbot and nobody fix the issue quickly, the change should be reverted.
https://pythondev.readthedocs.io/ci.html#revert-on-fail

Here, it was also a licensing issue.

Is there a way to get the buildbot to run on the PR before it's merged?
All the CI tests passed beforehand, and I don't have a Windows system to
test on myself...

Ping me once you're ready. I can help you on that. There is a way to run buildbots on a PR before it's merged. And I have a Windows 10 VM. But I don't think that I will be able to reproduce the issue on my Windows 10 VM.