Nice! Thanks for finding this. I don't suppose there's any chance this would qualify as a bugfix for 3.6.1? I've been holding off on working on https://github.com/pfmoore/pylaunch until 3.6 because 3.5 doesn't handle being in a subdirectory very well. It'd be a shame if this meant I could only really support 3.7+

But it is a pretty minor use case, so I'll live either way.

FWIW, I'm inclined to think we shouldn't be blindly overwriting things, at the very least we should check that what we're overwriting is what we expect. But my knowledge of this part of the interpreter is pretty much zero, so I'll defer to the experts.