Comment 3 for bug 1847361

@Billy - a few questions to complete the picture here:
1. Did this only fail on a major e.g. qemu 2.5 -> 3.1 upgrade or does it in your experience insist on the exact build ID so e.g. 2.5-1ubuntu1 -> 2.5-2ubuntu1 ? Depending on that answer the versioned package name becomes harder/easier - if you don't know please tell me then I will have to do some tests to confirm.
2. Most decisions to load-or-not are made on the initial instantiation, but as you say hotplug of e.g. new storage types might be an issue. What was your actual example to hit this - what did you hotplug (XML of guest and hotplug device if you have it still)