maria.insert_select failed in buildbot with timeout

maria.insert_select                      w2 [ fail ]  timeout after 900 seconds

        Test ended at 2017-05-08 15:29:36

Test case timeout after 900 seconds

== /mnt/buildbot/build/mariadb-10.2.6/mysql-test/var/2/log/insert_select.log == 

create table t1 (pk int primary key) engine=Aria;

insert into t1 values (1);

insert into t1 select sleep(2)+1 from t1;

connect  con1,localhost,root,,;

insert into t1 select 2 from t1;