supertype incompatibility with subclass classmethod

[bephinix]

I am currently trying to apply type hints to a base class and its subclasses which override a classmethod:

from abc import ABCMeta, abstractmethod
from typing import TypeVar, Type

class MyBase(metaclass=ABCMeta):
    @classmethod
    @abstractmethod
    def foo(cls) -> MyBase:
        pass


class MyChild(MyBase):
    @classmethod
    def foo(cls) -> MyChild:
        return MyChild()

_MyT = TypeVar("_MyT", bound=MyBase)

def bar(clazz: Type[_MyT]) -> _MyT:
    return clazz.foo()

Error:

example.py:19: error: Incompatible return value type (got "MyBase", expected "_MyT")

This seems to be incorrect, as returing MyBase is in bounds of _MyT.

I have found #2511 and its fix #7474 which should be merged in 0.761 but I still get this error.

Python: 3.8.1
MyPy: 0.761 (no custom flags)

[bephinix]

Using def foo(cls: Type[_MyT]) -> _MyT: solved this issue.