TypedDict with extra_items breaks control flow analyis of `in` operator

[moosbruggerj]

Describe the bug
When checking the existence of a key in a TypedDict which has extra_items defined, the unreachability analysis seems to assume every key is present.
Testing a normally defined key in the same dict behaves as expected.

Code or Screenshots

In the code below, pyright claims the print statement is never reached.

from typing import TypedDict

class Typed(TypedDict, extra_items=str):
    a: str

def test(d: Typed) -> None:
    if "b" in d:
        return
    print("here")

https://pyright-play.net/?strict=true&code=GYJw9gtgBALgngBwJYDsDmUkQWEMoAqiApgCYAiSAxjAFC1UA2AhgM6uEmkAURCZlGgBooxAB4wQzAPpIYxCKwC8rSQEoAXLSg6ozDVFUh6pYsFjFV3Ugb5k1UALQA%2BKADkwKYlt2ZzAIgAjf0wUKBttX10QYhgAVxAUSJ0EEFQYbn8AC2IY-zVaIA

VS Code extension or command-line
pyright 1.1409