Comment 12 for bug 667793

If one adds:

deb http://archive.ubuntu.com/ubuntu $codename-proposed restricted main multiverse universe

To the config template: /etc/cloud/templates/sources.list.tmpl

Then: rm -f /var/lib/cloud/sem/apt*
cloud-init-cfg- apt-update-upgrade
apt-get -y update

You're in business with the fix. Notice that this will install all proposed updates (and is not necessarily recommended).