`collections.abc.Set` does not support `Iterable` s in some dunder methods

While their implementation even specifically checks whether operand is an instance of an Iterable (for example: https://github.com/python/cpython/blob/c779f2324df06563b4ba3d70d0941e619ccaf5ff/Lib/_collections_abc.py#L628)

from collections.abc import Set
from typing import Iterable, Iterator


class S[T](Set[T]):
    def __init__(self, s: Iterable[T] | None = None) -> None:
        super().__init__()
        self._set: set[T] = set(s) if s else set()

    def __contains__(self, value: object) -> bool:
        return value in self._set

    def __iter__(self) -> Iterator[T]:
        return iter(self._set)

    def __len__(self) -> int:
        return len(self._set)

    def add(self, value: T) -> None:
        self._set.add(value)

    def discard(self, value: T) -> None:
        self._set.discard(value)

    def __repr__(self) -> str:
        return self._set.__repr__()

s = S[int]((1,2,3))
print(s & [4])
print(s | ("4",))
print(s - [1])
print(s ^ ("1",))

$ mypy t.py

t.py:29: error: Unsupported operand types for & ("S[int]" and "list[int]")  [operator]
t.py:30: error: Unsupported operand types for | ("S[int]" and "tuple[str]")  [operator]
t.py:31: error: Unsupported operand types for - ("S[int]" and "list[int]")  [operator]
t.py:32: error: Unsupported operand types for ^ ("S[int]" and "tuple[str]")  [operator]
Found 4 errors in 1 file (checked 1 source file)

$ python3 t.py

set()
{1, 2, 3, '4'}
{2, 3}
{1, 2, 3, '1'}

Start with linked pull request #14653 and the referenced Lib/_collections_abc.py implementation; compare the Set operator signatures with the runtime behavior shown in t.py. Done means the reported Iterable operands are represented correctly and the mypy command no longer reports those four operator errors.