Comment 24 for bug 1713490

Your guest already is pc-i440fx-bionic (because that is what the cloud archive is based on).
That means that qemu expects it to already run with the newer ipxe.

The only case I can think of is that this guest was started with
- qemu 1:2.11+dfsg-1ubuntu... installed
- ipxe not yet at 1.0.0+git-20180124.fbe8c52d-0ubuntu2

That never happens for Bionic as-is as people only get there with dist-upgrades (or new installs).
So they always have the new ipxe.
OTOH there isn't a struct dependency on >= 1.0.0+git-20180124.fbe8c52d-0ubuntu2

Therefore IMHO the problem is special to UCA, or almost broken (half) upgrades to Bionic

@James - I don't think we can safe guests started with Bionic level qemu but not Bionic level ipxe. Those just have to be restarted to get out of this (or temporarily downgrade on the target as Christian Z. did)
But we can think about adding a versioned dependency to avoid more of these conflicts to come up.
What is your opinion:
1. would you like the versioned dependency solution?
2. would you want that in UCA only or would you prefer to do that in Bionic as well?

P.S. if we go on we need a new bug for that.