I'm working on regrtest: https://bugs.python.org/issue36719
I introduced a subtle regression: when a test failed but passed when re-run, the whole build was considered as a failure. That explains the high number of emails today.
I already fixed regrtest: https://github.com/python/cpython/commit/837acc1957d86ca950433f5064fd06d09b5...
Well, it means that we still have a lot of flaky tests :-/
Night gathers, and now my watch begins. It shall not end until my death.