Row format replication from LONGBLOB COMPRESSED to LONGBLOB does not work

-- source include/have_binlog_format_row.inc

-- source include/master-slave.inc

connection master;

let mst=LONGBLOB COMPRESSED;

let slv=MEDIUMBLOB;

let cnv='ALL_LOSSY';

# This is to make sure that the compressed data is longer than 64K

SET column_compression_threshold=16*256*256;

--eval CREATE TABLE t1 (a $mst);

sync_slave_with_master;

connection slave;

SET @tmp=@@GLOBAL.SLAVE_TYPE_CONVERSIONS;

eval SET GLOBAL SLAVE_TYPE_CONVERSIONS = $cnv;

--eval ALTER TABLE t1 MODIFY a $slv;

connection master;

INSERT INTO t1 (a) VALUES (REPEAT('a',256*256));

SELECT LENGTH(a) FROM t1;

sync_slave_with_master;

SHOW CREATE TABLE t1;

SELECT LENGTH(a) FROM t1;

connection master;

DROP TABLE t1;

sync_slave_with_master;

connection slave;

SET GLOBAL SLAVE_TYPE_CONVERSIONS=@tmp;

--source include/rpl_end.inc

--------------------------------------------------------------------------

worker[1] Using MTR_BUILD_THREAD 300, with reserved ports 16000..16019

include/master-slave.inc

[connection master]

connection master;

SET column_compression_threshold=16*256*256;

CREATE TABLE t1 (a LONGBLOB COMPRESSED);;

connection slave;

connection slave;

SET @tmp=@@GLOBAL.SLAVE_TYPE_CONVERSIONS;

SET GLOBAL SLAVE_TYPE_CONVERSIONS = 'ALL_LOSSY';

ALTER TABLE t1 MODIFY a MEDIUMBLOB;;

connection master;

INSERT INTO t1 (a) VALUES (REPEAT('a',256*256));

SELECT LENGTH(a) FROM t1;

LENGTH(a)

65536

connection slave;

SHOW CREATE TABLE t1;

Table	Create Table

t1	CREATE TABLE `t1` (

  `a` mediumblob DEFAULT NULL

) ENGINE=MyISAM DEFAULT CHARSET=latin1

SELECT LENGTH(a) FROM t1;

LENGTH(a)

0

connection master;

DROP TABLE t1;

connection slave;

connection slave;

SET GLOBAL SLAVE_TYPE_CONVERSIONS=@tmp;

include/rpl_end.inc

compat/oracle.AAA2 'row'                 [ pass ]   1035

--------------------------------------------------------------------------

Field *Type_handler_blob_compressed::make_conversion_table_field(TABLE *table,

                                                      uint metadata,

                                                      const Field *target)

                                                      const

{

  return new(table->in_use->mem_root)

         Field_blob_compressed(Record_addr(true), Field::NONE,

                               &empty_clex_str,

                               table->s, 2, target->charset(),

                               zlib_compression_method);

}