> test_distutils will be difficult; the leak is around the "import xx" in
> Lib/distutils/tests/test_build_ext.py.
> 
> And Python/import.c says:
> /* To prevent initializing an extension module more than once, we keep a
> static dictionary 'extensions' keyed [...] by filename (for dynamically
> loaded modules). A copy of the module's dictionary is stored [...] 
> */
> 
> This dictionary keeps growing with random filenames in the temp
> directory. I can't see a way to clean it.

If it's just that (one leaked string per each extension module import),
I think we can live with it.