Some ball pythons do eat birds. But lots of ball pythons also get fixated on particular prey items and aren't interested in others.
Either way, the snake will most likely be accustomed to the general smells of the space it lives in. It will learn pretty quickly that there might be occasional whiffs of parrot, but that doesn't mean food - basically, the snake isn't going to spend its entire life in the food mood any more than you are able to stay constantly hyped up on adrenaline for years on end. It'll be fine.
