github howto reconfigure git repository if cloned original and forked later

gistfile1.sh

# so let's say you cloned repo someone/project like this
git clone git://github.com/someone/project.git

# you use it and then later on discover a bug.
# to fix it you create a fork on github to which you can
# write and issue a pull request, but now your origin is
# someone/project instead of you/project .
# fix it like this:

git remote rename origin upstream
git add origin git://github.com/you/project.git
git fetch origin
git push -u origin master

####### after this: ########

git fetch # fetches origin, so your fork

git checkout master
git pull # in your master branch: fetches your origin/master
         # and merges it into your master
git push # pushes to your fork

git checkout master
git fetch upstream # fetches the original someone/project
git merge upstream/master # in your master branch: merge
                          # someone/project into your master
git push # pushes to your fork