generic fails to narrow, something to do with using `NoReturn` on contravariant generic

from typing import Generic, Mapping, NoReturn, Sequence, TypeVar

T = TypeVar("T", contravariant=True)


class Foo(Generic[T]):
    ...


foo = Foo[int]()
bar = Foo[str]()

a1: Sequence[Foo[NoReturn]] = [foo]  # no error
a2: Sequence[Foo[NoReturn]] = [bar]  # no error

# error (this one seemed to be fixed around commit 32448b88370f8327c390f4e21666065c87ca95e2, then broken again)
a3: Sequence[Foo[NoReturn]] = [foo, bar]

a4: Sequence[Foo[NoReturn]] = [foo] or [bar]  # error

a5: Mapping[str, Sequence[Foo[NoReturn]]] = {  # error
    "foo": [foo],
    "bar": [],  # error goes away if you change this to [foo]
}

a6: Sequence[Sequence[Foo[NoReturn]]] = [[foo], []]  # error

https://mypy-play.net/?mypy=latest&python=3.10&gist=175deca029e02ea95af74f7c4a02856c

Start by running the six examples in the linked mypy-play reproduction and record the current diagnostics, especially for a3–a6. Compare the behavior with commit 32448b88370f8327c390f4e21666065c87ca95e2 as historical context. Done means the inconsistent errors for equivalent Foo[NoReturn] constructions are resolved without introducing new errors.