As [reported here](https://bugs.python.org/issue34632#msg343445), I submitted a pull request that passed all tests locally and in CI, but when accepted, build bots started to fail as a result of new files having been added to the project. It seems it's necessary in Makefile.pre.in to duplicate the git manifest to declare those directories... but only for buildbot builds. I don't fully understand why that is the case, but it would be nicer if there were protections from this footgun, especially since this issue may manifest several times in the same PR.

I can think of some ways to prevent this undesirable behavior:

- Include buildbot builds in the GitHub merge request checks.
- Add a GitHub bot that checks merge requests that create directories and alert the review of directories created if Makefile.pre.in doesn't include changes reflecting those directories.
- Remove the reliance on a separate directory listing in Makefile.pre.in.