Regression caused by #5565

[ilevkivskyi]

#5565 causes the following code to fail with Name 'x' already defined, while it is perfectly valid:

class C:
    def __init__(self, x: int) -> None:
        self.x = x
    @property
    def x(self) -> int: ...
    @x.setter
    def x(self, x: int) -> None: ...