The root cause of the problem here is not really having consistent
buildroots, but having improper packaging that doesn't account for all
possible variables. One thing we have internally at Red Hat is a mass
rebuild system that creates a buildroot with all packages installed,
attempts rebuilds of all packages, and for the builds that succeed, it
compares the resulting binary packages against the original ones to see if
things like filelist or dependencies have changed. It'd be nice to get
the equivalent of that for Fedora.
ALL packages installed becomes a bit more complex when you think about
fedora extras. ALL could become several thousand packages.
rpm comparison scripts for file list and dependencies abound from the
rhel rebuild projects. We can probably just snag one of those.