bpo-33632: Avoid signed integer overflow in the _thread module by ZackerySpytz · Pull Request #12729 · python/cpython

@ZackerySpytz The approach looks good to me, but I think it would be good to add a test here.

Is timeout something a user can specify? If timeout + now overflows, does it actually raise an error, or does it just set endtime to a negative number, causing this to time out immediately?

I also think it might be worth adding some of the details of exactly what user-facing behaviors will change with this patch to the changelog. "Avoid signed integer overflow" doesn't mean too much to me, out of context, and the BPO report is not much more detailed.