On a scene change the SCA_JoystickManager gets destroyed which in turn means all of it's joystick instances are released. Since SCA_PythonJoystick was just using a borrowed reference, this allowed the joystick to be freed. Now the joystick's refcount is incremented so that the SCA_PythonJoystick's joystick reference will survive across scene changes.
if bge.logic.joysticks[0]:
activate_player_one()
if bge.logic.joysticks[1]:
activate_player_two()
etc..
The interface exposed by SCA_PythonJoystick is very similar to the joystick logic brick except for one key difference: axis values are normalized to a -1.0 to 1.0 range instead of -32767 to 32767, which is what the logic brick exposed.
