pathlib in python3 has ".parent" property that returns parent-directory, and pathlib in master has ".parent(n)" method that returns n levels UP.
That sucks so much.
Python has a relatively large standard library (one of its selling points), and not everything in the standard library can be right the first time. No matter how long a Python release spends in beta, there are probably flaws that will only be discovered when people start using new modules to do their actual jobs (where they won't be using a beta version of Python).
In Python 1 and 2, if a standard library module had a flaw that required a backwards-incompatible change to fix, the flaw would have to remain there. In Python 3 they acknowledge that the first version may require backwards-incompatible changes.
"Note This module has been included in the standard library on a provisional basis. Backwards incompatible changes (up to and including removal of the package) may occur if deemed necessary by the core developers."
http://docs.python.org/3.4/library/pathlib.html