Referring to class attributes of a generic type

I apologize for posting my question here as an issue; I am doing this out of desperation since my original post on StackOverflow went unanswered for three weeks. Below is a near-verbatim copy from StackOverflow.

I have an abstract base class which defines several class attributes which are types themselves (i.e., nested types); the attributes are overridden in concrete derived classes inheriting from the abstract class. The concrete derived classes are used with several other classes which are type-annotated as generics, where the type parameter has a type constraint that it must be derived from the abstract class. I want these other classes (generics) to refer to the class attributes (nested types) of the concrete classes. The following example should demonstrate the idea:

import typing

class Base:
    A: typing.Type[Base]

class One(Base):
    class A(Base):  # overrides Base.A
        pass

class Two(Base):
    class A(One):  # overrides Base.A
        pass


T = typing.TypeVar('T', bound=Base)

class Foo(typing.Generic[T]):                 # the generic
    def foo(self, a: typing.Type[T.A]) -> T:  # <-- here, see T.A
        ...

f: Foo[Two] = Foo()
f.foo(Two.A)        # line 22 is here

MyPy v0.701 reports an error on line 22:

Argument 1 to "foo" of "Foo" has incompatible type "Type[A]"; expected "Type[Two]"

MyPy seems to ignore the attribute reference at T.A. How do I make it understand that I am trying to refer to the type available via the attribute .A? The attribute is guaranteed to be available because the type variable T is constrained to Base, which has A. Note that extending the set of generic types is not an option; I could elaborate on this but the explanation would be too specific to my application.

UPDATE: MyPy v0.711 with --new-semantic-analyzer yields a more comprehensible error message:

Name 'T.A' is not defined

L’issue ne mentionne aucun fichier ni test du dépôt ; commencez par l’exemple Python minimal et suivez la manière dont mypy gère les bornes de TypeVar, les annotations génériques et les références de type des attributs de classe. Le travail est considéré comme terminé lorsque le comportement de typage demandé dispose d’une implémentation ou d’une limitation définie et est couvert par un test de régression.