os.mkdir() errno inconsistency on Windows?

[Irmen de Jong]

Hi;

On windows (2000), Python 2.1:
Why does os.mkdir() return a different errno when trying to create an
already-existing directory, or trying to create the drive root directory?
See below:

>>> os.mkdir('d:\\test')
>>> os.mkdir('d:\\test')
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
OSError: [Errno 17] File exists: 'd:\\test'
>>> os.mkdir('d:\\')
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
OSError: [Errno 13] Permission denied: 'd:\\'
>>>

Thanks,
Irmen de Jong.

PS Why bother? Because I need to distinguish on exact Errno type, not only
on the OSError that's raised.