`super().__new__` inherited from Tuple doesn't match element type

Hi, when I inherit from Tuple[float, float, float], and pass a tuple of floats as an argument to super().__new__, I get an error saying that an Iterable[_T_co] was expected instead. As per the typeshed stub, _T_co is supposed to be the type of the tuple elements, so I guess it's not getting deduced correctly. Further, this works with tuple.__new__, so the involvement of super() must be to blame and the type signatures indeed aren't identical.

from typing import Tuple, Type, TypeVar

CoordsT = TypeVar('CoordsT', bound='Coords')
class Coords(Tuple[float, float, float]):
    def __new__(cls: Type[CoordsT]) -> CoordsT:

        reveal_type(super().__new__)
        # Revealed type is 'def [_T] (cls: Type[_T`-1], iterable: typing.Iterable[_T_co`1] =) -> _T`-1'
        reveal_type(tuple.__new__)
        # Revealed type is 'def [_T_co, _T] (cls: Type[_T`-1], iterable: typing.Iterable[_T_co`1] =) -> _T`-1'

        value = (0.0, 0.0, 0.0)
        result = tuple.__new__(cls, value)
        # fine
        super().__new__(cls, value)
        # error: Argument 2 to "__new__" of "tuple" has incompatible type "Tuple[float, float, float]"; expected "Iterable[_T_co]"

        return result

I'm not sure if it's mypy or typeshed that is responsible for the function signature of super's __new__, but I didn't find an overload for it in typeshed, so I suspect this is mypy's remit

Edit: mypy 0.770, Python 3.7.3

Start with the reproducer and compare the revealed types for super().__new__ and tuple.__new__. Inspect the referenced typeshed builtins.pyi signature, then trace how mypy handles the inherited __new__ call. Done means the shown super().__new__(cls, value) call accepts the tuple of floats without the reported type error.