IF NOT EXISTS does not work in CLONE GRAPH

[thewkgithub]

(root@nebula) [basketballplayer]> CREATE SPACE IF NOT EXISTS my_space_1 (vid_type=FIXED_STRING(30));
Execution succeeded (time spent 514µs/715.735µs)

(root@nebula) [basketballplayer]> CREATE SPACE IF NOT EXISTS my_space_2 AS my_space_1;
Execution succeeded (time spent 879µs/1.085528ms)

(root@nebula) [basketballplayer]> CREATE SPACE IF NOT EXISTS my_space_2 AS my_space_1;
[ERROR (-1005)]: Existed!

1. 先创建一个图空间, my_space_1
2. 使用克隆的方式, 去克隆出来my_space_2, 此时my_space_2不存在, 克隆成功.
3. 再克隆一次, 也就是当前图空间中存在my_space_2了, 此时再克隆就报-1005了..

说明在克隆图空间的时候, IF NOT EXISTS这个选项是无效的.和预期不一致.

[thewkgithub]

Version 3.3.0

[pengweisong]

@MuYiYong Should we ban the IF NOT EXISTS when clone space? Think about the case:

1. We have a Space B, which has different SpaceSpec with Space A
2. Now we execute CREATE SPACE IF NOT EXISTS B AS A; , if we return SUCCESS, it may have some problem: the A and B do not have the same SpaceSpec indeed.

[thewkgithub]

确实，哈哈。怎么想都不对。