False positive when callback protocol uses a function-scoped type variable

[robert-bn]

This appears to be a regression as the example code in #8177 fails to type check.

Please consider the following code:

from typing import  Protocol

class A[T,U]: ...

class BProto(Protocol):
    def __call__[T](self) -> A[list[T], T]: ...

def make_a[T]() -> A[list[T], T]: ...

def func1() -> BProto:
    return make_a

Pyright 1.1.405 run from command-line reports the following above the above code:

error: Type "() -> A[list[T@make_a], T@make_a]" is not assignable to return type "BProto"
    Type "() -> A[list[T@make_a], T@make_a]" is not assignable to type "() -> A[list[T@__call__], T@__call__]"
      Function return type "A[list[T@make_a], T@make_a]" is incompatible with type "A[list[T@__call__], T@__call__]"
        "A[list[T@make_a], T@make_a]" is not assignable to "A[list[T@__call__], T@__call__]"
          Type parameter "T@A" is covariant, but "list[T@make_a]" is not a subtype of "list[T@__call__]"
            "list[T@make_a]" is not assignable to "list[T@__call__]"
          Type parameter "U@A" is covariant, but "T@make_a" is not a subtype of "T@__call__"
            Type "T@make_a" is not assignable to type "T@__call__" (reportReturnType)

But make_a is an instance of BProto, so I would expect there not to be any type error.