My experience says the main reason people want to know whether the path is absolute is to figure out whether to do `Path.cwd() / path` or not. According to that MSDN page, they shouldn't because the path starts with "//" (that is, the last character and the existence of the share name are irrelevant here).

Both pathlib and ntpath are reasonably consistent in determining the "drive" of the path:
>>> splitdrive('\\\\server\\')[0]
'\\\\server\\'
>>> splitdrive('\\\\server')[0]
''
>>> Path('\\\\server\\').parts[0]
'\\\\server\\\\'
>>> Path('\\\\server').parts[0]
'\\'

I assume the bug in the last statement is what Antoine is referring to.

The difference in results then comes from how they determine roots.
>>> splitdrive('\\\\server\\')[1]
''
>>> splitdrive('\\\\server')[1]
'\\\\server'
>>> Path('//server/').root
'\\'
>>> Path('//server').root
'\\'

Pathlib always has a root, but splitdrive doesn't.

I'm not sure exactly which one to fix where, but hopefully that helps someone else figure it out.