Merge ~waveform/ubuntu/+source/livecd-rootfs:cloud-init-boot into ubuntu/+source/livecd-rootfs:ubuntu/devel

This looks good for the Pi POV. Sadly, we need to remember that our pi images are not the only consumer of the ubuntu-cpc project - this is something we use for cloud images as well. And those are not using ubuntu-image and the gadget concept. At least that should be our assumption.

I think we'd need to key this on something. We could do that per SUBARCH, and just use the boot partition for the cloud-init seed there, or maybe actually thinking of keying on IMAGEFORMAT. The problem with the second solution is that I'm not completely confident that IMAGEFORMAT=none is only used for our ubuntu-image based classic images (although it feels like it).

Whichever solution we decide on, remember that by default the ARCH, SUBARCH, IMAGEFORMAT etc. config options are not visible by default from hooks. For them to be visible, during auto/config we need to append those to things like the config/chroot file (grep for '>> config/'). Some variables are passed there like that. The cpc fixes hook already includes the /root/config/chroot file so it should all work then.

Ok, so Dave gave me a sign that this *is* actually raspi specific. Apparently that part of the hook is only executed whenever linux-image-raspi2 is installed. In light of that info, this feels like it's good to go.

We might need to want to disable raspi2 builds completely soon and maybe try re-branding the raspi3 ones to 'raspi'. Since without this change the old raspi2 preinstalled images will no longer have the ubuntu:ubuntu user.

Ah, hm, is it just me or that's the wrong merge target here? I'd say we all livecd-rootfs merges should be for lp:livecd-rootfs.