superseded update packages should be preserved

[D. Hugh Redelmeier]

| From: Jason L Tibbitts III <tibbs at math.uh.edu>

| Koji preserves everything except scratch builds.  Did it not have the
| package you were looking for?
| 
| http://koji.fedoraproject.org/koji/packageinfo?packageID=95

Great!  Thanks.  I didn't know that.

How is an "ordinary" user supposed to know that?  This is a real
question, not a rhetorical one.  I expect that there is a good answer.

PS: thanks to Matthew Woehlke and Josh Boyer for other replies.