'alter table nocache' and then 'alter table cache', unexpected warning message

[tiancaiamao]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

mysql> create table t (id int);
Query OK, 0 rows affected (0.01 sec)

mysql> alter table t cache;
Query OK, 1 row affected (0.01 sec)

mysql> alter table t nocache;
Query OK, 0 rows affected (0.00 sec)

mysql> alter table t cache;
Query OK, 0 rows affected, 1 warning (0.01 sec)

mysql> show warnings;
+---------+------+----------------------------------------+
| Level   | Code | Message                                |
+---------+------+----------------------------------------+
| Warning | 1062 | Duplicate entry '96' for key 'PRIMARY' |
+---------+------+----------------------------------------+
1 row in set (0.00 sec)

2. What did you expect to see? (Required)

No warning message

3. What did you see instead (Required)

Unexpected warning message ... although it doesn't affect the using

4. What is your TiDB version? (Required)

master 8134942

[tiancaiamao]

Ref #25293