PEP517

I'm not talking about using pip here (just invoking `setup.py install` or whatever will have the same issue) but rather any software where upstream expect data files to be installed to standard locations using their own setup.py, and all of their documentation refers to it and so on, which will stop working. The Python community hasn't done a great job of communicating this change.

But I'll reply more to the other comment rather than duplicating it.