> Since we already have os.rename, wouldn't it be better for shutil.move()
> to be closer to command line 'mv'? I think Facundo's approach should work.

I'd rather not do this. It might cause disasters for code that expects
the old semantics. If you want a way to do the "mv" semantics, propose
a new API.

shutil.move() still offers several things over os.rename(): deleting
the target even if os.rename() doesn't (it doesn't on Windows);
cross-filesystem moves implemented as copy.