main.mysqldump fails sporadically in buildbot

main.mysqldump 'innodb_plugin'           w4 [ fail ]

        Test ended at 2016-08-02 17:06:18

CURRENT_TEST: main.mysqldump

mysqldump: Couldn't find table: "non_existing"

mysqldump: Got error: 1356: "View 'test.v1' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them" when using LOCK TABLES

mysqldump: Couldn't execute 'SHOW FIELDS FROM `v1`': View 'test.v1' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them (1356)

mysqldump: Got error: 1083: "Field separator argument is not what is expected; check the manual" when executing 'SELECT INTO OUTFILE'

mysqldump: Got error: 1083: "Field separator argument is not what is expected; check the manual" when executing 'SELECT INTO OUTFILE'

mysqldump: Got error: 1083: "Field separator argument is not what is expected; check the manual" when executing 'SELECT INTO OUTFILE'

mysqldump: user2 has insufficent privileges to SHOW CREATE PROCEDURE `sp1`!

mysqldump: Got error: 1146: "Table 'test.???????????????????????' doesn't exist" when using LOCK TABLES

mysqlimport: ../nptl/pthread_mutex_lock.c:81: __pthread_mutex_lock: Assertion `mutex->__data.__owner == 0' failed.

mysqltest: At line 1762: exec of '/home/buildbot/maria-slave/power8-vlp03-bintar/build/client/mysqlimport --defaults-file=/home/buildbot/maria-slave/power8-vlp03-bintar/build/mysql-test/var/4/my.cnf --silent --use-threads=5 test /home/buildbot/maria-slave/power8-vlp03-bintar/build/mysql-test/var/4/tmp/t1.txt /home/buildbot/maria-slave/power8-vlp03-bintar/build/mysql-test/var/4/tmp/t2.txt' failed, error: 6, status: 0, errno: 0

Output from before failure:

test.t1: Records: 2  Deleted: 0  Skipped: 0  Warnings: 0

test.t2: Records: 2  Deleted: 0  Skipped: 0  Warnings: 0

The result from queries just before the failure was:

< snip >

/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;

/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;

DROP TABLE t1;

create table t1 (a text , b text);

create table t2 (a text , b text);

insert t1 values ("Duck, Duck", "goose");

insert t1 values ("Duck, Duck", "pidgeon");

insert t2 values ("We the people", "in order to perform");

insert t2 values ("a more perfect", "union");

select * from t1;

a	b

Duck, Duck	goose

Duck, Duck	pidgeon

select * from t2;

a	b

We the people	in order to perform

a more perfect	union

test.t1: Records: 2  Deleted: 0  Skipped: 0  Warnings: 0

test.t2: Records: 2  Deleted: 0  Skipped: 0  Warnings: 0