Commander: differentiate clearly between to arm and to disarm transition

src/modules/commander/Commander.cpp

@@ -2900,23 +2900,22 @@ Commander::run()
 			}
 		}
 
-		// check for arming state change
+		// check for arming state changes
 		if (_was_armed != _arm_state_machine.isArmed()) {
 			_status_changed = true;
+		}
 
-			if (_arm_state_machine.isArmed()) {
-				if (!_vehicle_land_detected.landed) { // check if takeoff already detected upon arming
+		if (!_was_armed && _arm_state_machine.isArmed() && !_vehicle_land_detected.landed) {
 			_have_taken_off_since_arming = true;
 		}
 
-			} else { // increase the flight uuid upon disarming
+		if (_was_armed && !_arm_state_machine.isArmed()) {
 			const int32_t flight_uuid = _param_flight_uuid.get() + 1;
 			_param_flight_uuid.set(flight_uuid);
 			_param_flight_uuid.commit_no_notification();
 
 			_last_disarmed_timestamp = hrt_absolute_time();
 		}
-		}
 
 		if (!_arm_state_machine.isArmed()) {
 			/* Reset the flag if disarmed. */