Use getFromKeyFieldsOr404 in slots() and allocateSlots()
Handling of the exception is done by the view decorator.
Patch by: Sverre Rabbelier
"Decorator for views that gzips pages if the client supports it."
from django.utils.decorators import decorator_from_middleware
from django.middleware.gzip import GZipMiddleware
gzip_page = decorator_from_middleware(GZipMiddleware)