F811 redefinition of unused incorrectly triggered for `__class__`

class A:
    @property
    def __class__(self):
        return int

    @__class__.setter
    def __class__(self, __type):
        raise NotImplementedError()

    @property
    def blah(self):
        return int

    @blah.setter
    def blah(self, __type):
        raise NotImplementedError()

This fails like this:

$ pyflakes foo.py 
foo.py:6: redefinition of unused '__class__' from line 2

I included a 2nd property definition to show that it wasn't happening normally. (Seems to be a special situation for __class__

$ pyflakes --version
2.0.0

Reproduce the report with the supplied class definition using pyflakes 2.0.0, then trace the linter's handling of the special __class__ property setter and compare it with the blah setter. Done means the valid __class__ property definition no longer produces an F811 warning while the existing redefinition check remains intact.