Comment 3 for bug 921774

It appears that we depend on the image the instance was originally created from to seed the new snapshot image with certain attributes (disk_format, container_format, architecture). So at this time, it is a requirement to have the original image available in order to take a snapshot. I do think we should redesign snapshotting so we don't have to depend on the original image, but I don't think that is feasible for the essex release timeframe.