Comment 13 for bug 1513529

I've realised that asking Scott to validate this wasn't the right call because he doesn't have a way of easily building images from -proposed. I have now built an image using the -proposed livecd-rootfs, and I see the following line in /etc/apt/sources.list of the produced image:

deb http://archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse

So this is indeed working.