Incorrect access to off-page column for indexed virtual column

CREATE TABLE t1(

  a INT NOT NULL UNIQUE,

  b INT NOT NULL,

  c TEXT GENERATED ALWAYS AS (a <> b) VIRTUAL,

  d TEXT NOT NULL,

  UNIQUE KEY (c(1)), KEY(d(1))

) ENGINE=InnoDB ROW_FORMAT=DYNAMIC;

SET @t = REPEAT('t',@@innodb_page_size);

INSERT INTO t1 (a,b,d) VALUES (1,0,@t), (0,0,@t);

--error ER_DUP_ENTRY

UPDATE t1 SET b = a;

REPLACE INTO t1 SET a = 0, b = 1, d = 'd';

SELECT * FROM t1;

CHECK TABLE t1;

DROP TABLE t1;

CREATE TABLE t1(

  a VARCHAR(1000) GENERATED ALWAYS AS ('1') VIRTUAL,

  b VARCHAR(1000) NOT NULL,

  c VARCHAR(1000) GENERATED ALWAYS AS (b) STORED,

  KEY (b(1)),

  KEY (a(1))

) ENGINE=InnoDB ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=1;

INSERT INTO t1(b) VALUES(REPEAT('b',1000));

DELETE FROM t1;

DROP TABLE t1;

mysqltest: At line …: query 'UPDATE t1 SET b = a' failed with wrong errno 2013: 'Lost connection to MySQL server during query', instead of 1062...

…

Version: '10.2.19-MariaDB-debug-log'  socket: '/dev/shm/10.2/mysql-test/var/tmp/mysqld.1.sock'  port: 16000  Source distribution

2018-10-25 16:57:29 140274706073344 [ERROR] InnoDB: Record in index `c` of table `test`.`t1` was not found on update: TUPLE (info_bits=0, 2 fields): {[1]t(0x74),[4]    (0x80000001)} at: COMPACT RECORD(info_bits=0, 2 fields): {[1]1(0x31),[4]    (0x80000001)}

mysqld: /mariadb/10.2m/storage/innobase/row/row0upd.cc:2436: dberr_t row_upd_sec_index_entry(upd_node_t*, que_thr_t*): Assertion `0' failed.