Those bugs will remain in alpha 8 if they don't know about them already, and the chances are the easy to find ones have already been ferreted out. That'd be part of why they want 50 more to begin with - more variety in systems, more variety in testing mechanisms, and more chance of software conflicts. By broadening the pool, the more obscure bugs become easier to surface, but nothing is gained by having us report 90% things that are already addressed in alpha 8.