mcs7238_regression_MCOL-830 fails randomly

mysqltest: At line 30: query 'select * from test.mcol830a union select * from test.mcol830b order by c1 desc' failed: ER_INTERNAL_ERROR (1815): Internal error: CrossEngineStep::execute() Set or verify credentials in CrossEngineSupport section of Columnstore.xml. (2006) (Server has gone away)

The result from queries just before the failure was:

< snip >

DROP TABLE IF EXISTS test.mcol830b;

CREATE TABLE test.mcol830a (

`c1` int(11) DEFAULT NULL,

`c2` varchar(64) DEFAULT NULL

) ENGINE=Columnstore DEFAULT CHARSET=utf8;

CREATE TABLE test.mcol830b (

`c1` int(11) DEFAULT NULL,

`c2` varchar(64) DEFAULT NULL

) ENGINE=MyISAM DEFAULT CHARSET=utf8;

insert into test.mcol830a values(1, 'cs测试');

insert into test.mcol830b values(2, 'myisam测试');

select * from test.mcol830a union select * from test.mcol830b order by c1 desc;

More results from queries before failure can be found in /var/tmp/mtr/log/mcs7238_regression_MCOL-830.log

Warnings from just before the error:

Error 1815 Internal error: CrossEngineStep::execute() Set or verify credentials in CrossEngineSupport section of Columnstore.xml. (2006) (Server has gone away)