Incompatible return type for overlapping signatures with regards to __new__ #10313

Bug Report

I came up with this when trying to fix itertools.combinations in typeshed to be a class instead of function.
It seems like mypy doesn't consider Tuple[T,T] to not overlap with Tuple[T, ...] with regards to return type.

I'm not sure if this is a bug or policy, but I would think that a variable length tuple is basically a union of all set length tuples and therefore should accept this.

To Reproduce

See the following code:
`
from typing import Generic, Literal, Tuple, overload,TypeVar

_T = TypeVar("_T")

class A(Generic[_T]):
@overload
def new(cls, a: Literal[1]) -> A[Tuple[int]]:
...
@overload
def new(cls, a: int) -> A[Tuple[int, ...]]:
...
def new(cls, a: int) -> A[Tuple[int, ...]]:
return super().new(cls)
`
mypy returns the following error:
error: Overloaded function signatures 1 and 2 overlap with incompatible return types

(also some error for the implementation return type, but it's irrelevant).

Your Environment

latest mypy, python 3.8.

Tried also on mypy playground with latest mypy and 3.9.