bulk build reuse old package for all matching dependencies?

["Jeremy C. Reed" <reed%reedmedia.net@localhost>]

Does anyone do bulk builds reusing old packages?

Anyone interested to setup a bulk build that keeps all old packages, only 
builds new packages for version/revision changes, and always reuses old 
matching packages for dependencies?

Maybe setup via cron daily so it would only do new builds of packages that 
have new version/revision changes.

This would be useful to catch problems where a dependency requirement was 
not changed, for example committer has new dependency installed but pkgsrc 
allows old one which is not good enough.

Do any of the bulk build frameworks easily/readily support this?