Comment 4 for bug 1217653

Able to confirm with lp:percona-xtradb-cluster trunk as well, changing wsrep_slave_threads on non-writer node to >1 (on writer node has no effect) produces

130902 17:25:00 [ERROR] Slave SQL: Could not execute Write_rows event on table sbtest.b; Cannot add or update a child row: a foreign key constraint fails (`sbtest`.`b`, CONSTRAINT `aid_fk` FOREIGN KEY (`aid`) REFERENCES `a` (`id`) ON DELETE CASCADE), Error_code: 1452; handler error HA_ERR_NO_REFERENCED_ROW; the event's master log FIRST, end_log_pos 94, Error_code: 1452
130902 17:25:00 [Warning] WSREP: RBR event 2 Write_rows apply warning: 151, 914
130902 17:25:00 [ERROR] WSREP: Failed to apply trx: source: 8ce7edb7-13c5-11e3-b1ae-36191a17aa6e version: 2 local: 0 state: APPLYING flags: 1 conn_id: 469 trx_id: 2191 seqnos (l: 917, g: 914, s: 913, d: 683, ts: 1378122900523716090)
130902 17:25:00 [ERROR] WSREP: Failed to apply app buffer: seqno: 914, status: WSREP_FATAL
         at galera/src/replicator_smm.cpp:apply_wscoll():52
         at galera/src/replicator_smm.cpp:apply_trx_ws():118
130902 17:25:00 [ERROR] WSREP: Node consistency compromized, aborting...