Fix functools.partial with Union of Any

[cdce8p]

Fixes

from functools import partial
from typing import Any

cls1: Any | Any
partial(cls1, 2)  # error: "Any | Any" not callable

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

kopf (https://github.com/nolar/kopf)
- kopf/_core/actions/invocation.py:127: error: Incompatible types in assignment (expression has type "partial[partial[object | Coroutine[None, None, object]]]", variable has type "partial[object | Coroutine[None, None, object | None] | None]")  [assignment]
+ kopf/_core/actions/invocation.py:127: error: Incompatible types in assignment (expression has type "partial[partial[object | Coroutine[None, None, object]]]", variable has type "partial[object | Coroutine[None, None, object]]")  [assignment]
- kopf/_core/actions/invocation.py:127: error: Argument 1 to "run" of "Context" has incompatible type "partial[object | Coroutine[None, None, object | None] | None]"; expected "Callable[[VarArg(Any), KwArg(Any)], partial[object | Coroutine[None, None, object]]]"  [arg-type]
+ kopf/_core/actions/invocation.py:127: error: Argument 1 to "run" of "Context" has incompatible type "partial[object | Coroutine[None, None, object]]"; expected "Callable[[VarArg(Any), KwArg(Any)], partial[object | Coroutine[None, None, object]]]"  [arg-type]
- kopf/_core/actions/invocation.py:127: note: "partial[object | Coroutine[None, None, object | None] | None].__call__" has type "Callable[[VarArg(Any), KwArg(Any)], object | Coroutine[None, None, object | None] | None]"
+ kopf/_core/actions/invocation.py:127: note: "partial[object | Coroutine[None, None, object]].__call__" has type "Callable[[VarArg(Any), KwArg(Any)], object | Coroutine[None, None, object]]"

[hauntsaninja]

Nice, thanks for finding! expandtype is a little interesting to me here, since there isn't a type variable mapping. I think maybe we just want to more explicitly handle unions... I opened #17284 , let me know what you think :-)

[cdce8p]

Fixed in #17284