a.sort() == b.sort() all the time

[Gribouillis]

When a is a list, a.sort() sorts the list in place, but the call to a.sort() returns None

>>> a = [1, 8, 4, 2]
>>> a.sort()
>>> a
[1, 2, 4, 8]
>>> a.sort() is None
True

Hence you are testing None == None, which always returns True.