MDEV#5552 Deadlock when inserting NULL column value

in column with UNIQUE index

References: lp:1276424

mysql-test/suite/galera/r/unique_key.result

+#
+# MDEV#5552 Deadlock when inserting NULL column value in column with
+# UNIQUE index
+#
+USE test;
+
+# On node_1
+CREATE TABLE t1(c1 INT DEFAULT NULL, UNIQUE KEY c1(c1)) ENGINE=INNODB;
+INSERT INTO t1 VALUES (NULL);
+INSERT INTO t1 VALUES (NULL);
+SELECT * FROM test.t1;
+c1
+NULL
+NULL
+
+# On node_2
+SELECT * FROM test.t1;
+c1
+NULL
+NULL
+
+# On node_1
+INSERT INTO t1 VALUES (1);
+UPDATE t1 SET c1=NULL WHERE c1=1;
+SELECT * FROM test.t1;
+c1
+NULL
+NULL
+NULL
+
+# On node_2
+SELECT * FROM test.t1;
+c1
+NULL
+NULL
+NULL
+
+# On node_1
+DELETE FROM t1 WHERE c1<=>NULL;
+SELECT * FROM test.t1;
+c1
+
+# On node_2
+SELECT * FROM test.t1;
+c1
+DROP TABLE t1;
+# End of test

mysql-test/suite/galera/t/unique_key.test

+--source include/galera_cluster.inc
+--source include/have_innodb.inc
+
+--echo #
+--echo # MDEV#5552 Deadlock when inserting NULL column value in column with
+--echo # UNIQUE index
+--echo #
+
+USE test;
+--echo
+--echo # On node_1
+--connection node_1
+CREATE TABLE t1(c1 INT DEFAULT NULL, UNIQUE KEY c1(c1)) ENGINE=INNODB;
+INSERT INTO t1 VALUES (NULL);
+INSERT INTO t1 VALUES (NULL);
+SELECT * FROM test.t1;
+
+--echo
+--echo # On node_2
+--connection node_2
+SELECT * FROM test.t1;
+
+
+--echo
+--echo # On node_1
+--connection node_1
+INSERT INTO t1 VALUES (1);
+UPDATE t1 SET c1=NULL WHERE c1=1;
+SELECT * FROM test.t1;
+
+--echo
+--echo # On node_2
+--connection node_2
+SELECT * FROM test.t1;
+
+--echo
+--echo # On node_1
+--connection node_1
+DELETE FROM t1 WHERE c1<=>NULL;
+SELECT * FROM test.t1;
+
+--echo
+--echo # On node_2
+--connection node_2
+SELECT * FROM test.t1;
+
+--let $galera_diff_statement = SELECT * FROM t1
+--source include/galera_diff.inc
+
+# Cleanup
+DROP TABLE t1;
+
+--source include/galera_end.inc
+--echo # End of test