docker/root/usr/bin/entrypoint already allows for the specification of USER, USER_UID, USER_GID. But since AllowedUsers is hardcoded in sshd_config, one cannot log in as a user different ftom git. This change substitutes ${USER} for git in the sshd_config template. Signed-off-by: Jeronimo Pellegrini <j_p@aleph0.info>for-closed-social