show create table with set is not compatible with mysql

[Defined2014]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

create table t(a set('a', 'b') charset binary);
show create table t;

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

mysql> show create table t;
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                              |
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| t     | CREATE TABLE `t` (
  `a` set('a','b') CHARACTER SET binary COLLATE binary DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin |
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+

3. What did you see instead (Required)

+-------+----------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                   |
+-------+----------------------------------------------------------------------------------------------------------------+
| t     | CREATE TABLE `t` (
  `a` set('a','b') DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin |
+-------+----------------------------------------------------------------------------------------------------------------+

4. What is your TiDB version? (Required)