Lucas Moscovicz <lmoscovicz@fb.com> [Tue, 11 Mar 2014 17:03:43 -0700] rev 20724
revset: added sort method in addset
We need this method to duck-type generatorset since this class is not going to
be used outside revset.py and we don't need to duck-type baseset.
This sort method will only do something when the addset is not already sorted
or is not sorted in the way we want it to be.