Comment 2 for bug 450124

After chatting with Julian, we decided to simply ensure that private PPAs will not have the restriction of serial builds for an architecture.

I would have liked to use a score threshold instead - so that any PPA could put urgent builds through in parallel when needed, but the current scoring mechanism is very relative and setting a hard-coded score threshold (rather than a corresponding score label, such as 'urgent') isn't nice. Branch attached.