Crash on replication on foreign key check with redundant indexes

[Vovan-VE]

We have multi-master setup with 3 nodes. When 2 nodes (say the currently are slaves) replicates from the other one which accept updates from a client, slaves can crash sometimes.

    [ERROR] Slave SQL: Could not execute Write_rows event on table DB.child; Cannot add
    or update a child row: a foreign key constraint fails (`DB`.`child`,
    CONSTRAINT `fk-child-parent` FOREIGN KEY (`parent_id`) REFERENCES `parent` (`id`)),
    Error_code: 1452; handler error HA_ERR_NO_REFERENCED_ROW; the event's master log FIRST,
    end_log_pos 204, Error_code: 1452

Crash is not consistent and probably depends from client traffic and/or concurrency.

After some not much proper refactoring a table schema became something like following:

    CREATE TABLE `child` (
      `id` INTEGER(11) NOT NULL AUTO_INCREMENT,
      `parent_id` INTEGER(11) NOT NULL,
      `foobar` INTEGER(11) NOT NULL,
      PRIMARY KEY(`id`),
      KEY `idx-parent_id` (`parent_id`),
      KEY `fk-parent` (`parent_id`, `foobar`),
      CONSTRAINT `fk-child-parent` FOREIGN KEY (`parent_id`) REFERENCES `parent` (`id`)
    ) ENGINE=InnoDB;

So, in the past there was FK `child`(`parent_id`,`foobar`) => `parent`(`id`,`foobar`).
Later that FK was replaced with FK `child`(`parent_id`) => `parent`(`id`).
And now there is redundant index (`parent_id`,`foobar`).

Look's like the chash did gone after we drop all such redundant indexes.

Affected versions:
* 5.6.35-80.0-56 Percona XtraDB Cluster (GPL), Release rel80.0, Revision 62752df, WSREP version 26.20, wsrep_26.20
* 5.6.36-82.0-56 Percona XtraDB Cluster (GPL), Release rel82.0, Revision de7a681, WSREP version 26.20, wsrep_26.20

[Vovan-VE (vovan-ve)]

Fail. Still crashing with the same table. Redundant indexes does not matter.