Duh. cmdqueue should be an instance variable, not a class variable. This was introduced in 1998 in rev. 1.13, where I imported extensive patches that, I am sad to say, I didn't review as carefully as I should have.

#ifndef Py_ENUMOBJECT_H
#define Py_ENUMOBJECT_H

/* Enumerate Object */

#ifdef __cplusplus
extern "C" {
#endif

PyAPI_DATA(PyTypeObject) PyEnum_Type;

#ifdef __cplusplus
}
#endif

#endif /* !Py_ENUMOBJECT_H */