[python-committers] Refleak tests in CI

Hi,

We don't have a PR check for refleaks. I would like one.

The buildbots are far too slow and unreliable to provide a sensible way to check for refleaks. It is nigh impossible to pick out errors in a PR from flaky tests, flaky machines and pre-existing errors.

Stopping refleaks at source would be great. But we need a PR checks for refleaks.

Unfortunately, refleaks tests are currently very slow. By splitting the tests into 3 or 4 groups we should be able to run refleak tests without slowing turn around too much.

I would rather have to wait a while to merge good code, than merge bad code quickly. I don't think the cost would be prohibitive.

Cheers, Mark.