There are assorted shenanigans in the dynamic module loading code that make
me think we should leave the associated loaders alone for now. Running
PyInit_* more than once isn't permitted by default, so reloading is a
no-op, and "loading again" *copies* the existing module. But modules can
opt in to allowing reinitialization by declaring a module state size of
zero :)

It's a solvable problem, but not an urgent one, and hence better addressed
when we're redesigning the associated C APIs for a PEP 451 based import
system.