>>> from abc import ABCMeta
>>> class AbstractMeta(type, metaclass=ABCMeta): pass
...
>>> class Meta1(AbstractMeta): pass
...
>>> class Meta2(AbstractMeta): pass
...
>>> class ClassA(metaclass=Meta1): pass
...
>>> isinstance(ClassA, Meta2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\miniconda\miniconda3\lib\abc.py", line 139, in __instancecheck__
    return _abc_instancecheck(cls, instance)
TypeError: __subclasscheck__() takes exactly one argument (0 given)


This is driven by the fact that the metaclass of AbstractMeta is ABCMeta; if I change its metaclass to something else that does not contain ABCMeta in the inheritance chain, isinstance returns False as expected.


Possibly related to Issue 2325?