Login as root and execute the following to switch a stoney cloud installation from stable (releases) to testing (pre-releases):
branch="1.2-pre" cd /usr/portage git remote set-branches --add origin "${branch}" git pull --rebase git checkout "${branch}" chown -R portage\: . cd /var/lib/layman/foss-cloud git remote set-branches --add origin "${branch}" git pull --rebase git checkout "${branch}" chown -R portage\: .