Poor RBR update performance with partitioned tables

This is related to the following upstream bug:

https://bugs.mysql.com/bug.php?id=73648

When binlog_format=ROW is set and a partitioned table is updated, the update seems to perform much slower than an equivalent update of a non-partitioned table.

Some MTR tests have been contributed to demonstrate this problem. They are in the attached zip archive. The results were reported as the following:

mariadb-10.1.31

bug.test 'innodb_plugin,row' [ pass ] 114205
bug.test_no_partition 'innodb_plugin,row' [ pass ] 22101

bug.test 'row,xtradb' [ pass ] 429822
bug.test_no_partition 'row,xtradb' [ pass ] 65829

mariadb 10.2.12

bug.test 'innodb,row' [ pass ] 161739
bug.test_no_partition 'innodb,row' [ pass ] 28501

mysql-5.6.39

bug.test [ pass ] 158594
bug.test_no_partition [ pass ] 20350

mysql 5.7.21

bug.test [ pass ] 37490
bug.test_no_partition [ pass ] 26441

MySQL 5.7 most likely performs better because of the introduction of native partitioning. Native partitioning was removed from MariaDB 10.2 during the 5.7 InnoDB merge. See MDEV-15223.