Whoa, Serhiy, your patch won't fly on Windows Vista.

For starter, the patch does not use target_is_directory=True option in os.symlink. It needs that option when creating symlink to the directory on Windows Vista.

The maximum depth that pathlib can do on Windows Vista is 4 (Remember, this line: "for depth in 0, 1, 2, 3, 10, 100"?).

More than that:
OSError: [WinError 1921] The name of the file cannot be resolved by the system:
'C:\\Users\\vajrasky\\Code\\cpython\\@test_4220_tmp\\testdir\\link5'

Not sure whether the bug is in pathlib.py or _getfinalpathname (from nt module).