refs MW-246

- created mtr test for testing explicit desyncing with RSU mode DDL

mysql-test/suite/galera/r/mysql-wsrep#247.result

+SET GLOBAL wsrep_desync=1;
+SET wsrep_OSU_method=RSU;
+CREATE TABLE t1 (i int primary key);
+SHOW VARIABLES LIKE 'wsrep_desync';
+Variable_name	Value
+wsrep_desync	ON
+SET GLOBAL wsrep_desync=0;
+DROP TABLE t1;
+SHOW VARIABLES LIKE 'wsrep_desync';
+Variable_name	Value
+wsrep_desync	OFF

mysql-test/suite/galera/t/mysql-wsrep#247.test

+#
+# codership/mysql-wsrep/247 MW-246 -
+# DDL with RSU fails if node is desynced upfont
+#
+
+--source include/galera_cluster.inc
+--source include/have_innodb.inc
+
+--connection node_1
+
+SET GLOBAL wsrep_desync=1;
+
+SET wsrep_OSU_method=RSU;
+
+CREATE TABLE t1 (i int primary key);
+
+SHOW VARIABLES LIKE 'wsrep_desync';
+
+SET GLOBAL wsrep_desync=0;
+
+DROP TABLE t1;
+SHOW VARIABLES LIKE 'wsrep_desync';
+