bulk builds and failed packages

[Jared McNeill <jmcneill%invisible.ca@localhost>]

Hi folks.

I've got a setup running for NetBSD/earmv7hf 7.0 that basically does cvs 
update, bulkbuild, rsync in a loop. Mostly good, but I have one issue I 
have yet to solve.

Since the destination has limited disk space, I need to pass --delete to 
rsync. My concern is that if a package fails to build on one of the 
iterations, there will be a possibly long window where the package will be 
unavailable. The turnaround time for "spot error in build, check in fix, 
wait for current bulk build to complete, pick up change, wait for next 
bulk build to complete" could be weeks, even with the limited set of 
packages I am building.

So what I'm looking for is some kind of solution that in the event of a 
package build failure, grab the last known binary package (probably want 
to grab the closest matching version) if present and stuff that in with 
the other packages. There is always a chance that the old binary package 
will not work but I would rather try it than not have it.

Thoughts?