Optimisation in prefetch_related_objects

            if len(obj_list) == 0:

                break

            current_lookup = LOOKUP_SEP.join(attrs[0:level+1])

            if current_lookup in done_queries:

                # Skip any prefetching, and any object preparation

                obj_list = done_queries[current_lookup]

                continue

            # Prepare objects:

            good_objects = True

            for obj in obj_list:

                # Since prefetching can re-use instances, it is possible to have

                # the same instance multiple times in obj_list, so obj might

                # already be prepared.

                if not hasattr(obj, '_prefetched_objects_cache'):

                    try:

                        obj._prefetched_objects_cache = {}

                        # now.

                        good_objects = False

                        break

                else:

                    # Since prefetching can re-use instances, it is possible to

                    # have the same instance multiple times in obj_list. So we

                    # can reach this branch either because we did all of

                    # obj_list already, or because we did 'obj' earlier in this

                    # iteration over obj_list. In the first case we could

                    # shortcut and exit the loop, but not in the second.

                    continue

            if not good_objects:

                break

                                 "prefetch_related()." % lookup)

            if prefetcher is not None and not is_fetched:

                # Check we didn't do this already

                current_lookup = LOOKUP_SEP.join(attrs[0:level+1])

                if current_lookup in done_queries:

                    obj_list = done_queries[current_lookup]

                else:

                obj_list, additional_prl = prefetch_one_level(obj_list, prefetcher, attr)

                # We need to ensure we don't keep adding lookups from the

                # same relationships to stop infinite recursion. So, if we