[Merge] lp:~rbalint/livecd-rootfs/livecd-rootfs-autopkgtest-fix into lp:livecd-rootfs

[Balint Reczey]

I was unable to reproduce the issue in qemu, but running from PPA worked while failed at a different stage, after kpartx again:
https://objectstorage.prodstack4-5.canonical.com/v1/AUTH_77e2ada1e7a84929a74ba3b87153c0ac/autopkgtest-zesty-rbalint-scratch/zesty/amd64/l/livecd-rootfs/20170419_220558_38a44@/log.gz

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https://code.launchpad.net/~rbalint/livecd-rootfs/livecd-rootfs-autopkgtest-fix/+merge/322767
Your team Ubuntu Core Development Team is requested to review the proposed merge of lp:~rbalint/livecd-rootfs/livecd-rootfs-autopkgtest-fix into lp:livecd-rootfs.