rocksdb.unique_check fails in buildbot with wrong errno

rocksdb.unique_check                     w4 [ fail ]

        Test ended at 2018-06-25 06:32:22

CURRENT_TEST: rocksdb.unique_check

mysqltest: At line 118: query 'insert into t1 values (1,2)' failed with wrong errno 1062: 'Duplicate entry '1' for key 'PRIMARY'', instead of 1205...

The result from queries just before the failure was:

< snip >

connection con2;

commit;

select * from t2;

id	id2	value

2	1	2

truncate table t2;

connection con1;

set debug_sync='rocksdb.update_write_row_after_unique_check SIGNAL parked1 WAIT_FOR go1';

insert into t1 values (1,1);

connection con2;

set debug_sync='rocksdb.update_write_row_after_unique_check SIGNAL parked2 WAIT_FOR go2';

insert into t2 values (1,1,1);

connection default;

set debug_sync='now WAIT_FOR parked1';

set debug_sync='now WAIT_FOR parked2';

Warnings:

Warning	1639	debug sync point wait timed out

connection con3;

set session rocksdb_lock_wait_timeout=1;

insert into t1 values (1,2);

More results from queries before failure can be found in /dev/shm/var/4/log/unique_check.log

 - skipping '/dev/shm/var/4/log/rocksdb.unique_check/'