Code review comment for lp://qastaging/~terceiro/lava-master-image-scripts/debian-is-supported

Testing for features has the foul smell of autotools - it is slower and ultimately just as broken. I'd rather keep it to "we know this platform works". Eventually I'd remove older releases so that we don't really pretend to support them.

Also, there is the difference between 'it seems to work' and 'we support it'. I think this makes sense here.