ER_DATA_TOO_LONG or Assertion `!is_set() || (m_status == DA_OK_BULK && is_bulk_op())' failed upon UPDATE on RocksDB table

INSTALL SONAME 'ha_rocksdb';

CREATE TABLE t1 (

    pk INT PRIMARY KEY,

    a VARCHAR(16) CHARACTER SET utf8,

    b INT,

    KEY(a)

) ENGINE=RocksDB;

--error ER_DATA_TOO_LONG

UPDATE t1 SET b = 1 WHERE a LIKE 'bar%';

mysqld: /data/src/10.2/sql/sql_error.cc:380: void Diagnostics_area::set_ok_status(ulonglong, ulonglong, const char*): Assertion `!is_set() || (m_status == DA_OK_BULK && is_bulk_op())' failed.

191008  2:40:02 [ERROR] mysqld got signal 6 ;

#7  0x00007fd23e77ef12 in __GI___assert_fail (assertion=0x55b652d9ae78 "!is_set() || (m_status == DA_OK_BULK && is_bulk_op())", file=0x55b652d9adb0 "/data/src/10.2/sql/sql_error.cc", line=380, function=0x55b652d9b1c0 <Diagnostics_area::set_ok_status(unsigned long long, unsigned long long, char const*)::__PRETTY_FUNCTION__> "void Diagnostics_area::set_ok_status(ulonglong, ulonglong, const char*)") at assert.c:101

#8  0x000055b6522d97b3 in Diagnostics_area::set_ok_status (this=0x7fd228005cb0, affected_rows=0, last_insert_id=0, message=0x7fd238ab13c0 "Rows matched: 0  Changed: 0  Warnings: 2") at /data/src/10.2/sql/sql_error.cc:380

#9  0x000055b65228c5b3 in my_ok (thd=0x7fd228000b00, affected_rows=0, id=0, message=0x7fd238ab13c0 "Rows matched: 0  Changed: 0  Warnings: 2") at /data/src/10.2/sql/sql_class.h:4547

#10 0x000055b6523f804c in mysql_update (thd=0x7fd228000b00, table_list=0x7fd228012560, fields=..., values=..., conds=0x7fd228012f88, order_num=0, order=0x0, limit=18446744073709551615, handle_duplicates=DUP_ERROR, ignore=false, found_return=0x7fd238ab1870, updated_return=0x7fd238ab1920) at /data/src/10.2/sql/sql_update.cc:1023

#11 0x000055b652307f0d in mysql_execute_command (thd=0x7fd228000b00) at /data/src/10.2/sql/sql_parse.cc:4014

#12 0x000055b652313d8e in mysql_parse (thd=0x7fd228000b00, rawbuf=0x7fd228012468 "UPDATE t1 SET b = 1 WHERE a LIKE 'bar%'", length=39, parser_state=0x7fd238ab2200, is_com_multi=false, is_next_command=false) at /data/src/10.2/sql/sql_parse.cc:7759

#13 0x000055b652302097 in dispatch_command (command=COM_QUERY, thd=0x7fd228000b00, packet=0x7fd22808d6f1 "UPDATE t1 SET b = 1 WHERE a LIKE 'bar%'", packet_length=39, is_com_multi=false, is_next_command=false) at /data/src/10.2/sql/sql_parse.cc:1831

#14 0x000055b6523009eb in do_command (thd=0x7fd228000b00) at /data/src/10.2/sql/sql_parse.cc:1384

#15 0x000055b652455ca5 in do_handle_one_connection (connect=0x55b65564d860) at /data/src/10.2/sql/sql_connect.cc:1336

#16 0x000055b652455a10 in handle_one_connection (arg=0x55b65564d860) at /data/src/10.2/sql/sql_connect.cc:1241

#17 0x000055b652c86a40 in pfs_spawn_thread (arg=0x55b655670b10) at /data/src/10.2/storage/perfschema/pfs.cc:1862

#18 0x00007fd2402f44a4 in start_thread (arg=0x7fd238ab3700) at pthread_create.c:456

#19 0x00007fd23e83bd0f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:97

CURRENT_TEST: bug.4282

mysqltest: At line 10: query 'UPDATE t1 SET b = 1 WHERE a LIKE 'bar%'' failed: 1406: Data too long for column 'a' at row 1

Warnings:

Warning	1815	Internal error: Indexed column test.t1.a uses a collation that does not allow index-only access in secondary key and has reduced disk space efficiency in primary key.