IsolatedAsyncioTestCase `__del__` could be dangerous

[graingert]

It looks like in IsolatedAsyncioTestCase when debug() crashes it doesn't teardown the event loop, in addition it seems that if the loop isn't torn down it will happen in __del__ which means thread local sensitive functions like set_event_loop get called via the GC from potentially the wrong thread

Originally posted by @graingert in #95898 (comment)

[gvanrossum]

Apart from a reproducer it would be nice if your issue description was more clearly stating the problem. Quoting from the middle of another discussion is just confusing.

[graingert]

I had a go at undrafting the issue, I still need to make a reproducer

[gvanrossum]

Hm... I had sort of assumed that debug() was intentionally not cleaning anything up on failure -- TestCase.debug() doesn't either (it has a special case for @skip though).

PS. There is no such thing as a draft issue.