Good way to recycle previous quarter's binary packages?

[John Klos <john%ziaspace.com@localhost>]

Hi,

When switching build machines from one quarter to the next, how do people 
recycle the previous quarter's binaries, excluding the ones which would 
need to be rebuilt?

I wrote a quick script that simply compares the list of dependencies and 
versions of binary packages with the list of dependencies and versions 
from the next quarter's pkgsrc and copies if the lists are the same. Is 
there a better way?

Thanks,
John