Attribute assignments through a base class don't call __setattr__ defined in a subclass #1242

class Base:
    def __init__(self) -> None:
        self.y = 0

    def set_y(self) -> None:
        self.y = 1


class Derived(Base):
    def __setattr__(self, name: str, value: object) -> None:
        print("setattr", name, value)
        super().__setattr__(name, value)


def set_through_base(b: Base) -> None:
    b.y = 2


d = Derived()
d.set_y()
set_through_base(d)