When reviewing issue 32904 I noticed that os.getcwdb still calls the CRT _getcwd function. Apparently this was overlooked when implementing PEP 529. For example:

    >>> os.getcwd()
    'C:\\Temp\\Lang\\αβγδ'
    >>> os.getcwdb()
    b'C:\\Temp\\Lang\\a\xdf?d'

Not only is the encoding wrong, but because the CRT uses GetFullPathNameA (the CRT's implementation of _getcwd is convoluted, IMO), the call fails if the current directory exceeds MAX_PATH. Python 3.6+ on Windows 10 otherwise supports long paths.