Problem with resolving MutableMapping with type subscripts

[anselor]

This worked fine is version 1.14.1 and earlier but starting in 1.15.0 I get TypeError: ABCMeta is not subscriptable.

I have code that's something like this:

from typing import TYPE_CHECKING

if TYPE_CHECKING:
    MyBaseType = MutableMapping[str, Any]
else:
    MyBaseType = MutableMapping

class MyCustomClass(MyBaseType):
    ...