[Merge] livecd-rootfs:fix-kassel into livecd-rootfs:ubuntu/bionic

[Brian Murray]

Review: Approve

Let's stop the immediate noise (build failure emails) and get this landed. However, I do think we should investigate stopping builds of this.
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https://code.launchpad.net/~ubuntu-core-dev/livecd-rootfs/+git/livecd-rootfs/+merge/414282
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