Cloning this repository:

git clone git://gitorious.org/drupal_trac_service/drupal_trac_service.git drupal_trac_service
cd drupal_trac_service

Add this repository as a remote to an existing local repository:

git remote add drupal_trac_service git://gitorious.org/drupal_trac_service/drupal_trac_service.git
git fetch drupal_trac_service
git checkout -b my-local-tracking-branch drupal_trac_service/master_or_other_branch