MXS-2326: Add hint cloning test case

The test checks that the steps taken to reproduce the bug no longer result
in a failure to route the query correctly.

maxscale-system-test/CMakeLists.txt

@@ -919,7 +919,10 @@ add_test_executable(mxs2115_version_string.cpp mxs2115_version_string replicatio
 add_test_executable(mxs2295_change_user_loop.cpp mxs2295_change_user_loop mxs2295_change_user_loop LABELS REPL_BACKEND)
 
 # MXS-2300: Prune session command history
-add_test_executable(mxs2300_history_pruning.cpp mxs2300_history_pruning mxs2300_history_pruning LABELS REPL_BACKEND)
+add_test_executable(mxs2300_history_pruning.cpp mxs2300_history_pruning mxs2300_history_pruning LABELS readwritesplit REPL_BACKEND)
+
+# MXS-2326: Routing hints aren't cloned in gwbuf_clone
+add_test_executable(mxs2326_hint_clone.cpp mxs2326_hint_clone mxs2326_hint_clone LABELS readwritesplit REPL_BACKEND)
 
 ############################################
 # BEGIN: binlogrouter and avrorouter tests #

maxscale-system-test/cnf/maxscale.cnf.template.mxs2326_hint_clone

@@ -0,0 +1,53 @@
+[maxscale]
+threads=###threads###
+log_info=1
+
+[server1]
+type=server
+address=###node_server_IP_1###
+port=###node_server_port_1###
+protocol=MySQLBackend
+
+[server2]
+type=server
+address=###node_server_IP_2###
+port=###node_server_port_2###
+protocol=MySQLBackend
+
+[server3]
+type=server
+address=###node_server_IP_3###
+port=###node_server_port_3###
+protocol=MySQLBackend
+
+[server4]
+type=server
+address=###node_server_IP_4###
+port=###node_server_port_4###
+protocol=MySQLBackend
+
+[MySQL Monitor]
+type=monitor
+module=mysqlmon
+servers=server1,server2,server3,server4
+user=maxskysql
+password=skysql
+monitor_interval=1000
+
+[hint]
+type=filter
+module=hintfilter
+
+[RW Split Router]
+type=service
+router=readwritesplit
+servers=server1,server2,server3,server4
+user=maxskysql
+password=skysql
+filters=hint
+
+[RW Split Listener]
+type=listener
+service=RW Split Router
+protocol=MySQLClient
+port=4006

maxscale-system-test/mxs2326_hint_clone.cpp

@@ -0,0 +1,29 @@
+/**
+ * MXS-2326: Routing hints aren't cloned in gwbuf_clone
+ */
+
+#include "testconnections.h"
+
+int main(int argc, char** argv)
+{
+    TestConnections test(argc, argv);
+    Connection c = test.maxscales->rwsplit();
+    test.expect(c.connect(), "Connection should work: %s", c.error());
+
+    std::string correct_id = c.field("SELECT @@server_id -- maxscale route to server server4");
+
+    test.tprintf("Executing session command");
+    test.expect(c.query("SET @a = 1"), "SET should work: %s", c.error());
+
+    test.tprintf("Forcing a reconnection to occur on the next query by blocking the server");
+    test.repl->block_node(3);
+    test.maxscales->wait_for_monitor();
+    test.repl->unblock_node(3);
+    test.maxscales->wait_for_monitor();
+
+    test.tprintf("Executing a query with a routing hint to a server that the session is not connected to");
+    test.expect(c.check("SELECT @@server_id -- maxscale route to server server4",
+                        correct_id), "Hint should be routed to the same server");
+
+    return test.global_result;
+}