from __future__ import annotations bug?

[Joseph Garvin]

```
from __future__ import annotations
from typing import Generic, TypeVar

T = TypeVar("T")
class Foo(Generic[T]): ...
class Bar(Foo[Buzz]): ... # NameError here
class Buzz: ...
```

This will error, despite the __future__ import, because cpython is trying
to look up Buzz before it's defined, even though we have supposedly
prevented annotations from being processed. I realize that Class[Args] is
allowed in that area in general and isn't always type annotation related,
but does this mean that even with PEP 649 that forward references will
still be needed?