Currently, the rollback functionality is just a security feature.
Consequently, the only way to restore a backup is to do manually
outside fredistrano (eg. via ssh).
Actually, we never use this option. Initially, we implemented this
feature to protect the production files that aren't contained in SVN.
We were afraid that a bad configuration of fredistrano could result in
the deletion of these files by the rsync command.
By the way, for all versioned files, don't forget that you can deploy
a previous revision of your application! This is precisely how we
rollback in our environment.
euphrate_ylb