Re: [libvirt] avoid new "make check" failure and fix a related bug

In reviewing/testing some incoming patches, I noticed a new "make check" failure. There were two problems: - not diagnosing an invalid host UUID. The lack of this diagnostic made it slightly more challenging to track down the next problem: - not accommodating the fact that our template now contains an invalid line; before the addition of "host_uuid", each commented-out sample line was valid.