Use getFromKeyFieldsOr404 in slots() and allocateSlots()
Handling of the exception is done by the view decorator.
Patch by: Sverre Rabbelier
from django.core.management.base import NoArgsCommand
class Command(NoArgsCommand):
help = "Validates all installed models."
requires_model_validation = False
def handle_noargs(self, **options):
self.validate(display_num_errors=True)