Message 402264 - Python tracker

It looks like the `_thread` module does not actually expose `PyThread_exit_thread` --- the similarly named `thread_PyThread_exit_thread` just raises SystemExit.

From a search in the codebase, it appears `PyThread_exit_thread` is currently used only to kill threads when they attempt to acquire the GIL during finalization.

Also, if it is changed to no longer kill the thread, it would probably make sense to rename it, e.g. to `PyThread_stop_thread_during_finalization`.