In short The sheep won't turn right. You can see the project here. (screenshot at the bottom)
I went slightly beyond the scope of pset0 but really wanted to create a great foundation for a platformer (and a little nostalgia for this old sheep that ran around my desktop in my school days).
I got gravity, jumping and everything working perfectly. Since adding the detectors and altering my code (so that I can recognise collisions with the environment), turning right has broken.
For the life of me I cannot see what I've done wrong logically. Anyone else see?