Code review comment for lp:~florent.x/pyflakes/1097061-unittest2

I'd prefer not to see Pyflakes gain a setuptools dependency (even an optional one). setuptools causes far more problems than it solves. Regardless, as a part of this branch, the addition seems out of place - Pyflakes' setup.py did not declare a dependency on Twisted previously (in other words, it's an unrelated "enhancement").