sysconfig path schemes don't follow the os.name pattern
The sysconfig docs say: "These schemes are stored in sysconfig under unique identifiers based on the value returned by os.name." The docs list five supported schemes, with start with either "nt" or "posix", values of os.name.
PyPy adds two schemes: "pypy" and "pypy_nt". These don't follow the same pattern. Shouldn't they be "posix_pypy" and "nt_pypy"? Or at least "pypy_posix" and "pypy_nt"?