When to rebuild pbulk setup and how?

[Mayuresh <mayuresh%acm.org@localhost>]

I was facing several problems with my pbulk based bulkbuild setup, where
packages were failing with bulkbuild, but were getting built fine manually
in the same sandbox.

Most packages failed for libz, some for a few others.

So I am deleting /usr/pbulk and recreating from scratch by running
pbulk.sh again. Also deleting any existing packages built by previous
setup.

Wonder, if such intervention is needed once in a while, and exactly when
if so. If yes, is there a systematic way to update the /usr/pbulk prefix,
other than just deleting and recreating?

-- 
Mayuresh