mypy Type error for a class with an imported metaclass

Please provide more information to help us understand the issue:

• Are you reporting a bug, or opening a feature request? bug
• Please insert below the code you are checking with mypy,
  or a mock-up repro if the source is private. We would appreciate
  if you try to simplify your case to a minimal repro.
  Here is an example class I am working with.

@enum.unique
class MyEnumClass(Enum, metaclass=MyEnumMetaClass):
    OUT_OF_STOCK = "Out of Stock"
    LOW_STOCK = "Low Stock"
    IN_STOCK = "In Stock"
    EXCESS = "Excess"

I am making a change where I am importing the MyEnumMetaClass class from a PIP package now, whereas before it was located within the same project as this class.

• What is the actual behavior/output?
  With MyEnumMetaClass imported, whenever I create a MyEnumClass instance, mypy gives me the following error:
  error: The type "Type[MyEnumClass]" is not generic and not indexable
• What is the behavior/output you expect?
  I expect mypy to succeed here, given that the code is the same, it is just imported from a package now.

Beginne mit dem bereitgestellten minimalen Enum- und Metaklassenbeispiel und prüfe es einmal mit lokal definiertem MyEnumMetaClass und einmal, wenn es aus einem Paket importiert wird. Verfolge den Unterschied in mypys Behandlung der Klasse und bestätige, dass die importierte Version den gemeldeten Fehler, dass sie nicht generisch und nicht indizierbar ist, nicht mehr erzeugt.