Comment 0 for bug 1513529

When we were poking around under bug 1177432 we found that /etc/apt/sources.list that is built into the image does not match that of an installed system. This /etc/apt/sources.list is used if cloud-init did not re-write the file (such as woudl be used if you mounted the image directly and ran apt-get update).

Example showing the problem:
$ qemu-img create -f qcow2 -b wily/release-20151029/ubuntu-15.10-server-cloudimg-amd64-disk1.img /tmp/disk.img
$ sudo mount-image-callback /tmp/disk.img --read-only chroot _MOUNTPOINT_ cat /etc/apt/sources.list
deb http://archive.ubuntu.com/ubuntu/ wily main restricted universe multiverse
deb http://archive.ubuntu.com/ubuntu/ wily-updates main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu/ wily-security main restricted universe multiverse

What we'd like to see here is exactly what we just added to cloud-init.
For reference, as attached to bug 1177432, see trusty [1] and wily [2] examples.

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[1] https://launchpadlibrarian.net/224142290/trusty-sources.list
[2] https://launchpadlibrarian.net/224142308/wily-sources.list

Related bugs:
 * bug 1177432 [SRU] Enable backports in cloud-init archive template