Moving zipimporter to Python code is harder than it sounds: we don't want to break the ability to ship the standard library itself inside a zipfile.

If you try to move zipimporter to pure Python, you could easily end up with a *very* ugly bootstrapping problem, on par with that already encountered when hacking on importlib._bootstrap.

In fact, the path of least resistance here might actually be to implement zipimporter directly *in* importlib._bootstrap.