Login HAML location for Ubuntu 12.04 is as follows

/opt/gitlab/embedded/service/gitlab-rails/app/views/layouts/devise.html.haml

Edit the file as you need. Then run

sudo gitlab-ctl restart
to apply the edited HAML and restart gitlab.

The old way of calling bundle rake or gitlab-ctl rake is useless now. You don’t have to use it nor you should use it.