Something (possibly [1], but that change is at best cryptic) has
changed such that we don't get correct /etc/os-release files
installed. This flows on to grub half-installing itself, enough to
not fail the build but not enough to make something bootable.
Installing the -cloud release package gets it back, and seems like a
sane choice for dib.
[1] 617b1bed34
Change-Id: Iff0413887fad798273b2bfcb140cc07f36d54a04
efa3f3675a