update a GitHub forked repository

gistfile1.txt

# http://stackoverflow.com/questions/7244321/how-to-update-a-github-forked-repository

# Add the remote, call it "upstream":
git remote add upstream https://github.com/whoever/whatever.git

# Fetch all the branches of that remote into remote-tracking branches,
# such as upstream/master:
git fetch upstream

# Make sure that you're on your master branch:
git checkout master

# Update your local master:
git pull upstream master

# Rewrite your master branch so that any commits of yours that
# aren't already in upstream/master are replayed on top of that
# other branch:
git rebase upstream/master