Bash: Git – Rename an email address in all old commits.

gistfile1.sh

# Rename an email address in all old commits.
# WARNING: Will change all your commit SHA1s.
# Based off of the script from here:
#  http://coffee.geek.nz/how-change-author-git.html
git filter-branch -f --commit-filter '
        if [ "$GIT_COMMITTER_EMAIL" = "joern.zaefferer@googlemail.com" ];
        then
                GIT_AUTHOR_EMAIL="joern.zaefferer@gmail.com";
                GIT_COMMITTER_EMAIL="joern.zaefferer@gmail.com";
                git commit-tree "$@";
        else
                git commit-tree "$@";
        fi' HEAD
git push --force

Doesn't work. Deletes all commits.
That git push --force is a terrible idea to put into an automatic script that can delete all your commits