I'd prefer an optional flag to rename() too.
I really don't like having different functions that achieve the same thing.
It's not obvious to infer from 'replace' its real intent, since it
doesn't match any standard syscall/library.
Ideally, this should be made an option to rename(), especially since
on Unix this will just perform a standard rename.
Another advantage of options over new functions is that it reduces
boilerplate code (i.e. argument parsing, addition to posix_methods,
repeating OS idiosyncrasies/conditional compilation blocks, docstring,
documentation block...).
But I remember Martin thinks that the os module should just be a thin wrapper around underlying syscalls/libraries (but we already have listdir() and friends).