Fix memory leak

Requires priority/multifactor plugin with multiple partitions per job

src/plugins/priority/multifactor/priority_multifactor.c

@@ -757,6 +757,7 @@ static uint32_t _get_priority_internal(time_t start_time,
 			      job_ptr->priority_array[i]);
 			i++;
 		}
+		list_iterator_destroy(part_iterator);
 	}
 	/* Priority 0 is reserved for held jobs */
 	if (priority < 1)