divide zone into itself

[HarrisChu]

(root@nebula) [(none)]> show zones
+----------------+-------------+-------+
| Name           | Host        | Port  |
+----------------+-------------+-------+
| "default_zone" | "127.0.0.1" | 19430 |
| "z1"           | "127.0.0.1" | 12547 |
| "z1"           | "127.0.0.1" | 13029 |
| "z1"           | "127.0.0.1" | 12848 |
+----------------+-------------+-------+
Got 4 rows (time spent 2393/8533 us)

Fri, 14 Jan 2022 18:21:23 CST

(root@nebula) [(none)]> show hosts
+-------------+-------+----------+--------------+----------------------+------------------------+
| Host        | Port  | Status   | Leader count | Leader distribution  | Partition distribution |
+-------------+-------+----------+--------------+----------------------+------------------------+
| "127.0.0.1" | 12547 | "ONLINE" | 0            | "No valid partition" | "No valid partition"   |
| "127.0.0.1" | 12848 | "ONLINE" | 0            | "No valid partition" | "No valid partition"   |
| "127.0.0.1" | 13029 | "ONLINE" | 0            | "No valid partition" | "No valid partition"   |
| "127.0.0.1" | 19430 | "ONLINE" | 0            | "No valid partition" | "No valid partition"   |
| "Total"     |       |          | 0            |                      |                        |
+-------------+-------+----------+--------------+----------------------+------------------------+
Got 5 rows (time spent 3014/12862 us)

Fri, 14 Jan 2022 18:21:27 CST

(root@nebula) [(none)]> DIVIDE zone "z1" into "z1" (127.0.0.1:12547) "z2" (127.0.0.1:13029,127.0.0.1:12848)
[ERROR (-1005)]: Existed!

Fri, 14 Jan 2022 18:21:32 CST

shall we support this?