load data incorrect with default fields terminate when tab's space exists in file

[yexiaoli88]

• **dble version：5.6.29-dble-9.9.9.9-16ae8083a9edeb67ab102cded51446e27d7ee2f5-20190628070902 **
• preconditions ：

CREATE TABLE sharding_four(ID INT NOT NULL,FirstName VARCHAR(20),LastName VARCHAR(20),Department VARCHAR(20),Salary INT);

2.test.txt with tab:

201     "Mazojys        ddd     ggg"    "Fxoj"  "Finance"       7800

3.turn on backend mysql 's general log

• configs：

schema.xml

<schema name="testdb" sqlMaxLimit="100" dataNode="dn4">
       <table name="sharding_four" dataNode="dn1,dn2,dn3,dn4" rule="hash-four"/>
    </schema>

rule.xml

<tableRule name="hash-four">
        <rule>
            <columns>id</columns>
            <algorithm>four-long</algorithm>
        </rule>
  </tableRule>
 <function name="four-long" class="Hash">
        <property name="partitionCount">4</property>
        <property name="partitionLength">1</property>
    </function>

• steps：
  1.execute follows in dble:

mysql> load data infile "/opt/test.txt" into table sharding_four  FIELDS   OPTIONALLY ENCLOSED BY '"'   LINES TERMINATED BY '\n';
Query OK, 1 row affected (0.00 sec)
Records: 1  Deleted: 0  Skipped: 0  Warnings: 0

2. verify if load data works fine

mysql> select * from sharding_four;
+-----+-----------+----------+------------+--------+
| ID  | FirstName | LastName | Department | Salary |
+-----+-----------+----------+------------+--------+
| 201 | Mazojys  | ddd      | ggg       |      0 |
+-----+-----------+----------+------------+--------+
2 rows in set (0.00 sec)

3. find out sql executed in mysql from general log:

2019-07-30T10:14:38.028049Z	 1001 Query		LOAD DATA LOCAL INFILE '/opt/test.txt' INTO TABLE sharding_four COLUMNS OPTIONALLY ENCLOSED BY '"' LINES TERMINATED BY '
'

4. execute the same load data sql in mysql：

mysql> load data infile "/opt/test.txt" into table sharding_four FIELDS   OPTIONALLY ENCLOSED BY '"'  LINES TERMINATED BY '\n';
Query OK, 1 row affected (0.00 sec)
Records: 1  Deleted: 0  Skipped: 0  Warnings: 0

mysql> select * from sharding_four;
+-----+-----------------+----------+------------+--------+
| ID  | FirstName       | LastName | Department | Salary |
+-----+-----------------+----------+------------+--------+
| 201 | Mazojys	ddd	ggg | Fxoj     | Finance    |   7800 |
+-----+-----------------+----------+------------+--------+
1 row in set (0.00 sec)

• expect result：
  1..the second column in step2 should be ' Mazojys ddd ggg' ,the same as it in step4

• real result：
  1.the second column in step2 is ' "Mazojys '

• supplements：

[yexiaoli88]

related #1248

[wjl1619]

verified on version: 5.6.29-dble-9.9.9.9-e2603d1945eec66ed3fd11f2608027ab324ca483-20190802031757