Use `LOOKUP_SEP` in `get_or_create`.

            return self.get(**lookup), False

        except self.model.DoesNotExist:

            try:

                params = dict([(k, v) for k, v in kwargs.items() if '__' not in k])

                params = dict((k, v) for k, v in kwargs.items() if LOOKUP_SEP not in k)

                params.update(defaults)

                obj = self.model(**params)

                sid = transaction.savepoint(using=self.db)

                obj.save(force_insert=True, using=self.db)

                transaction.savepoint_commit(sid, using=self.db)

                return obj, True

            except IntegrityError as e:

            except IntegrityError:

                transaction.savepoint_rollback(sid, using=self.db)

                exc_info = sys.exc_info()

                try: