Code review comment for lp:~villemvainio/ipython/ip-sets-warn

I actually ended up applying a cleaner version of this here:

http://bazaar.launchpad.net/~fdo.perez/ipython/trunk-dev/revision/1174

They are functionally equivalent (for py>= 2.4) and the one I applied has less try/excepts. so let's just drop this branch altogether, we don't need it anymore.