Even though I've never written a single line of Python, the challenge was clear and simple to solve (I'm winner #17).
To the people complaining about them not marking all solutions as correct, it does state in the "About" tab that you have to solve it by either editing one line or adding a new one.
That being said, they should've made it clearer and more visible. I actually failed all the qualifiers except for one because I added/changed more than one line.
If you're gonna participate (which you should!), make sure you take a look at the "About" page.