Change Committer Email on a git repository

gistfile1.bash

# name 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 [ "$GIT_COMMITTER_EMAIL" = "<OLDMAIL>" ];
        then
                GIT_AUTHOR_EMAIL="<NEWMAIL>";
                git commit-tree "$@";
        else
                git commit-tree "$@";
        fi' HEAD
git push --force