Synchroniser un fork avec le repo dont il est issu :

Si ce n'est pas déjà fait :

    git remote add upstream https://github.com/ORIGINAL_OWNER/ORIGINAL_REPOSITORY.git

Puis :

    git fetch upstream
    git checkout master
    git merge upstream/master

Autre technique ( http://stackoverflow.com/questions/3903817/pull-new-updates-from-original-github-repository-into-forked-github-repository/3903835#3903835 )

$ cd github-services
$ git remote add upstream git://github.com/pjhyett/github-services.git
$ git fetch upstream

// then: (like "git pull" which is fetch + merge)
$ git merge upstream/master master

// or, better, replay your local work on top of the fetched branch
// like a "git pull --rebase"
$ git rebase upstream/master