StatusModel status managers don't have custom methods of a default manager

[EliasCampos]

Problem

Sometimes you might want to add a custom manager with custom queryset methods to a model that inherits StatusModel. (for example, via .as_manager() method of a queryset class):

class CustomQuerySet(models.QuerySet):

    def custom_qs_method(self):
        return self.filter(feedback='')


class Consultation(StatusModel):
    STATUS = Choices('PENDING', 'FINISHED')
    feedback = models.TextField(default='')

    objects = CustomQuerySet.as_manager()

Later, you might need to apply the methods to a queryset that filtered by a status value. I guess, it would be nice to use a manager for a specific status, provided by StatusModel (in this way we don't need to add .filter(status=value) each time or to define extra methods in custom managers). So, It would be nice to be able to do something like that:

Consultation.FINISHED.custom_qs_method()

But currently it's not possible, because status manager is a QueryManager instance, and it doesn't inherit a custom methods of default manager. I propose to complement current implementation of the status managers, to include custom qs/manager methods to a status manager.