I think you may need to instrument TemporaryDirectory._cleanup to be sure, but it sounds like its being run twice.

now, you're not using it like a context manager (at least as far as your code shows), so it must be happening from the weakref.

https://docs.python.org/3/library/weakref.html#weakref.finalize is the relevant docs for that.

The code looks ok as long as finalize triggers once and only once. Perhaps it should call the finalize() rather than manually calling _cleanup, in cleanup, but I don't see that that should make much difference. I would have thought it a deliberate attempt to avoid some bit of code (e.g. the resource warning), but since its a shared helper, thats not it.

And finalize._exitfunc looks entirely sane to me.

So - I suggest adding a call to print_stack in TemporaryDirectory._cleanup, to see the entire stack, and then hopefully we'll see two such printouts when this error happens, and be able to pinpoint how it's being called twice.