message: [storage] fix before unit test error
diff: @@ -129,7 +129,7 @@ fn test_two_level_storage() {
  let value6 = cache_storage
  .get(TRANSACTION_INFO_PREFIX_NAME, id.to_vec())
  .unwrap();
  - assert!(value6.unwrap().is_empty());
  + assert_eq!(CacheObject::transform(value6), CacheObject::None);
  let value7 = db_storage
  .get(TRANSACTION_INFO_PREFIX_NAME, id.to_vec())
  .unwrap();
  