autotest: fix mavproxy switch test

The order in which we fix the environment means that we need to be
listening on the correct port for rc values - so just fix it in the test

Tools/autotest/rover.py

@@ -619,6 +619,8 @@ Brakes have negligible effect (with=%0.2fm without=%0.2fm delta=%0.2fm)
         self.customise_SITL_commandline([
             "--rc-in-port", "5502",
         ])
+        ex = None
+        try:
             self.load_mission(self.arming_test_mission())
             self.wait_ready_to_arm()
             fnoo = [(1, 'MANUAL'),
@@ -632,6 +634,17 @@ Brakes have negligible effect (with=%0.2fm without=%0.2fm delta=%0.2fm)
                 mavproxy.send('switch %u\n' % num)
                 self.wait_mode(expected)
             self.stop_mavproxy(mavproxy)
+        except Exception as e:
+            self.print_exception_caught(e)
+            ex = e
+
+        # if we don't put things back ourselves then the test cleanup
+        # doesn't go well as we can't set the RC defaults correctly:
+        self.customise_SITL_commandline([
+        ])
+
+        if ex is not None:
+            raise ex
 
     def test_setting_modes_via_mavproxy_mode_command(self):
         fnoo = [(1, 'ACRO'),