type year should have an unsigned flag

[jackysp]

Please answer these questions before submitting your issue. Thanks!

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

mysql> show create table testyear;
+----------+-------------------------------------------------------------------------------------------+
| Table    | Create Table                                                                              |
+----------+-------------------------------------------------------------------------------------------+
| testyear | CREATE TABLE `testyear` (
  `i` year(4) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+----------+-------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> select * from testyear;
Field   1:  `i`
Catalog:    `def`
Database:   `test`
Table:      `testyear`
Org_table:  `testyear`
Type:       YEAR
Collation:  binary (63)
Length:     4
Max_length: 0
Decimals:   0
Flags:      UNSIGNED ZEROFILL NUM 


0 rows in set (0.00 sec)

2. What did you expect to see?
   Flags: UNSIGNED ZEROFILL NUM

3. What did you see instead?
   Flags: ZEROFILL NUM

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?
   eec6899

[zhexuany]

@jackysp title is kinda confusing. Do you mean "type year should have an unsigned flag, but it does not have currently"?