Subtle change to the query that checks whether a node's OS supports linktest:
change the query to check nodes.node_id instead of nodes.phys_nodeid against the reserved.node_id. This means the query now returns FBSD-JAIL for vnodes rather than NULL for the OS. I ran the query against every current experiment in the DB and the only other changes were: * plab nodes return RHL_PLAB instead of NULL. As long as linktest is not an osfeature of that image (it isn't) then this fix is compatible * pc2000s, which host IXPs, now only return one row in the query. Previously they would return a row for "pc17X" and for "ixpN". This is probably not what we wanted anyway.