unexpect error result when insert too long data with unimportant suffix to varchar column

Bug Report

1. What did you do? If possible, provide a recipe for reproducing the error.

CREATE TABLE `history1` (
  `h_c_id` int(11) DEFAULT NULL,
  `h_c_d_id` tinyint(4) DEFAULT NULL,
  `h_c_w_id` smallint(6) DEFAULT NULL,
  `h_d_id` tinyint(4) DEFAULT NULL,
  `h_w_id` smallint(6) DEFAULT NULL,
  `h_date` datetime DEFAULT NULL,
  `h_amount` decimal(6,2) DEFAULT NULL,
  `h_data` varchar(24) DEFAULT NULL,
  KEY `fkey_history_11` (`h_c_w_id`,`h_c_d_id`,`h_c_id`),
  KEY `fkey_history_21` (`h_w_id`,`h_d_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;

set sql_mode='ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';

INSERT INTO history1  (h_c_d_id, h_c_w_id, h_c_id, h_d_id,  h_w_id, h_date, h_amount, h_data)  VALUES (1,3,1450,1,3,NOW(),3242,'name-rwmwt name-uzqka       ');

2. What did you expect to see?

Query OK, 1 row affected, 1 warning (0.01 sec)

mysql> show warnings;
+-------+------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| Level | Code | Message                                                                                                                                                   |
+-------+------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| Error | 1064 | You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'warning' at line 1 |
+-------+------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

3. What did you see instead?

mysql> INSERT INTO history1  (h_c_d_id, h_c_w_id, h_c_id, h_d_id,  h_w_id, h_date, h_amount, h_data)  VALUES (1,3,1450,1,3,NOW(),3242,'name-rwmwt name-uzqka       ');
ERROR 1406 (22001): Data too long for column 'h_data' at row 1

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?

Git Commit Hash: None
Git Branch: None
UTC Build Time: None
GoVersion: None
Race Enabled: false
TiKV Min Version: 2.1.0-alpha.1-ff3dd160846b7d1aed9079c389fc188f7f5ea13e
Check Table Before Drop: false