`__orig_bases__` returns indirect generic bases instead of direct bases, causing mismatch with `__bases__`

[chirizxc]

Bug report

Bug description:

from abc import ABC, abstractmethod

class A[T](ABC):
    @abstractmethod
    async def get(self) -> T: ...

class B(A[int], ABC):
    @abstractmethod
    async def get_specific(self): ...

class C:
    pass

class D(C, B):
    async def get(self):
        return 1
    async def get_specific(self):
        return 2

print(D.__orig_bases__) # (__main__.A[int], <class 'abc.ABC'>)
print(D.__bases__)      # (<class '__main__.C'>, <class '__main__.B'>)

CPython versions tested on:

3.13

Operating systems tested on:

Windows

[JelleZijlstra]

This is part of why we added types.get_original_bases. The problem is that the __orig_bases__ attribute isn't set on D, so it falls back to the parent class.

Solution: use documented, public functions instead of undocumented dunders.

>>> types.get_original_bases(D)
(<class '__main__.C'>, <class '__main__.B'>)