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

この issue にはリポジトリのファイルやテストが記載されていないため、最小限の Python 例から始め、mypy が TypeVar の境界、ジェネリックアノテーション、クラス属性の型参照をどのように処理するかを追跡してください。要求された型付けの動作について、実装または制限が定義され、回帰テストでカバーされていれば完了です。