Load the imported data into the database, timestamp column, TiDB and MySQL behavior inconsistent

[together-wang]

Bug Report

Please answer these questions before submitting your issue. Thanks!

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

$ cat a.csv
2019-02-01 00:00:00

load data local infile "/data1/a.csv" into table test_table1;

Table structure：
MySQL [lianxi]> show create table test_table1 \G
*************************** 1. row ***************************
Table: test_table1
Create Table: CREATE TABLE test_table1 (
stime datetime DEFAULT NULL COMMENT '时间',
id bigint(20) DEFAULT NULL COMMENT '编号',
zone varchar(100) DEFAULT NULL COMMENT '地区',
cnt bigint(20) DEFAULT NULL COMMENT '次数',
updated timestamp NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
updated1 timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '更新时间',
updated2 timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
KEY idx_id (id),
KEY idx_zone (zone)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='测试表';

2. What did you expect to see?

MySQL [lianxi]> select * from test_table1 where stime='2019-02-01 00:00:00';
+---------------------+------+------+------+---------+---------------------+---------------------+
| stime | id | zone | cnt | updated | updated1 | updated2 |
+---------------------+------+------+------+---------+---------------------+---------------------+
| 2019-02-01 00:00:00 | NULL | NULL | NULL | NULL | 2019-05-15 19:41:02 | 2019-05-15 19:41:02 |
+---------------------+------+------+------+---------+---------------------+---------------------+

3. What did you see instead?

MySQL [test]> select * from test_table1 where stime='2019-02-01 00:00:00';
+---------------------+------+------+------+---------+---------------------+---------------------+
| stime | id | zone | cnt | updated | updated1 | updated2 |
+---------------------+------+------+------+---------+---------------------+---------------------+
| 2019-02-01 00:00:00 | NULL | NULL | NULL | NULL | 0000-00-00 00:00:00 | 0000-00-00 00:00:00 |
+---------------------+------+------+------+---------+---------------------+---------------------+

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

Release Version: v2.1.8
Git Commit Hash: 9a2d2da
Git Branch: HEAD
UTC Build Time: 2019-04-12 07:48:47
GoVersion: go version go1.11.2 linux/amd64
Race Enabled: false
TiKV Min Version: 2.1.0-alpha.1-ff3dd160846b7d1aed9079c389fc188f7f5ea13e
Check Table Before Drop: false