MXS-2464: Add test case

The bug appears when a session command that is executed on the master
fails. The logic in the code doesn't take this case into consideration
when it processes failed connections.

maxscale-system-test/CMakeLists.txt

@@ -951,6 +951,9 @@ add_test_executable(pam_authentication.cpp pam_authentication pam_authentication
 # MXS-2520: Allow master reconnection on reads
 add_test_executable(mxs2520_master_read_reconnect.cpp mxs2520_master_read_reconnect mxs2520_master_read_reconnect LABELS REPL_BACKEND readwritesplit)
 
+# MXS-2464: Crash in route_stored_query with ReadWriteSplit
+add_test_executable(mxs2464_sescmd_reconnect.cpp mxs2464_sescmd_reconnect mxs2464_sescmd_reconnect LABELS REPL_BACKEND readwritesplit)
+
 ############################################
 # BEGIN: binlogrouter and avrorouter tests #
 ############################################

maxscale-system-test/cnf/maxscale.cnf.template.mxs2464_sescmd_reconnect

@@ -0,0 +1,29 @@
+[maxscale]
+threads=###threads###
+
+[MySQL-Monitor]
+type=monitor
+module=mysqlmon
+servers=###server_line###
+user=maxskysql
+password=skysql
+monitor_interval=1000
+backend_read_timeout=1
+backend_connect_timeout=1
+
+[RW-Split-Router]
+type=service
+router=readwritesplit
+servers=###server_line###
+user=maxskysql
+password=skysql
+delayed_retry_timeout=1
+transaction_replay=true
+
+[RW-Split-Listener]
+type=listener
+service=RW-Split-Router
+protocol=MySQLClient
+port=4006
+
+###server###

maxscale-system-test/mxs2464_sescmd_reconnect.cpp

@@ -0,0 +1,35 @@
+/**
+ * MXS-2464: Crash in route_stored_query with ReadWriteSplit
+ * https://jira.mariadb.org/browse/MXS-2464
+ */
+
+#include "testconnections.h"
+
+int main(int argc, char* argv[])
+{
+    TestConnections test(argc, argv);
+
+    test.maxscales->connect();
+    std::thread thr([&]() {
+                        sleep(5);
+                        test.tprintf("block node 0");
+                        test.repl->block_node(0);
+                        test.tprintf("wait for monitor");
+                        test.maxscales->wait_for_monitor(2);
+                        test.tprintf("unblock node 0");
+                        test.repl->unblock_node(0);
+                    });
+
+    constexpr const char* query = "SET @a = (SELECT SLEEP(10))";
+    test.set_timeout(60);
+    test.tprintf("%s", query);
+    test.try_query(test.maxscales->conn_rwsplit[0], query);
+    test.stop_timeout();
+
+    test.tprintf("disconnect");
+    test.maxscales->disconnect();
+    test.tprintf("join");
+    thr.join();
+
+    return test.global_result;
+}