Fast Forward Your Fork
# kudos to https://github.com/drewlesueur
# stolen from here: https://github.com/blog/266-fast-forward-your-fork#comment-11535
git checkout -b upstream/master
git remote add upstream git://github.com/documentcloud/underscore.git
git pull upstream master
git checkout master // [my master branch]
git merge upstream/master
git push origin master