When the table config with UpperCase name ,the ER can not be recognized

[sunsun314]

• dble version：
  master-9.9.9.9
• preconditions ：
  no
• configs：

schema.xml

<?xml version="1.0"?>
<!DOCTYPE dble:schema SYSTEM "schema.dtd">
<dble:schema xmlns:dble="http://dble.cloud/">
<schema name="testdb"  dataNode="dn1">
	<table name="tableA" rule="testShard" dataNode = "dn1,dn2"></table>
	<table name="tableB" rule="testShard" dataNode = "dn1,dn2"></table>
    </schema>
    <dataNode name="dn1" dataHost="host1" database="db1"></dataNode>
    <dataNode name="dn2" dataHost="host1" database="db2"></dataNode>
    <dataNode name="dn3" dataHost="host1" database="db3"></dataNode>
    <dataNode name="dn4" dataHost="host1" database="db4"></dataNode>
    <dataHost name="host1"  maxCon="50" minCon="1" balance="0" switchType="1" slaveThreshold="100" tempReadHostAvailable="0" >
        <heartbeat>select user()</heartbeat>
        <writeHost host="host1m" url="10.186.24.37:3308" user="root" password="123456">
        </writeHost>
    </dataHost>
</dble:schema>

rule.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE dble:rule SYSTEM "rule.dtd">
<dble:rule xmlns:dble="http://dble.cloud/">
<tableRule name="testShard">
        <rule>
            <columns>id</columns>
            <algorithm>test</algorithm>
        </rule>
    </tableRule>

<function name="test" class="Hash">
        <property name="partitionCount">2</property>
        <property name="partitionLength">1</property>
    </function>

• steps：
  execute 'explain select * from tableb,tablea where tableb.id = tablea.id;
  '
• expect result：
  the route can be turned into ER join ,send to mysql with join
• real result：
  the sql can not be recognized as ER join

/label ~BUG

[yexiaoli88]

verified on version: 5.6.29-dble-9.9.9.9-283f45d-20180717102231