NamedTuples fail to narrow with `issubclass()`

[ygale]

Bug Report

issubclass() fails to narrow type[A] to type[M] when A and M are unrelated NamedTuples. A plain if guard block treats the branch as unreachable instead. A comprehension filter keeps the unnarrowed type instead.

Note: This is NOT a duplicate of #21635 or #21677. Although each of these three issues has the same surface bug behavior -- mypy gets confused during type narrowing and bails out by setting the type to Never, causing the reported symptoms -- each has a completely different root cause for the confusion.

To Reproduce

from typing import NamedTuple, reveal_type

class A(NamedTuple):
    a: int

class M(NamedTuple):
    m: int

cls: type[A] = A
if issubclass(cls, M):
    reveal_type(cls)

Expected Behavior

reveal_type(cls) reports type[<subclass of "A" and "M">].

Actual Behavior

Success: no issues found in 1 source file

No reveal_type note at all -- the branch is silently treated as unreachable.

Second repro (comprehension)

from typing import NamedTuple, reveal_type

class A(NamedTuple):
    a: int

class M(NamedTuple):
    m: int

alist: list[type[A]] = [A]
mlist: list[type[M]] = [cls for cls in alist if issubclass(cls, M)]
reveal_type(mlist)

Expected Behavior

No error, mlist is list[type[M]].

Actual Behavior

error: List comprehension has incompatible type List[type[A]]; expected List[type[M]]  [misc]

Environment

• Mypy version used: mypy 2.2.0+dev (main branch)
• Mypy command-line flags: none
• Mypy configuration options from mypy.ini (and other config files): nothing special
• Python version used: 3.12