Type inference regression involving filter(None, ...) #8093
Description
This example started generating errors after #8077:
from typing import Optional, TypeVar, Iterable, Iterator, List
_T = TypeVar('_T')
def filter(__function: None, __iterable: Iterable[Optional[_T]]) -> List[_T]: ...
x: Optional[str]
# Need type annotation for 'pagelets'
# List item 0 has incompatible type "Optional[str]"; expected "None"
pagelets = filter(None, [x])The issue also happens with Python 2 filter(), at least.
cc @ilevkivskyi