Ubuntu's multisearch surprise

As per my comment above, a better solution might be for the packagers to work directly on the upstream source instead of on local trees. That way the upstream source supports packaging for all distributions interested in shipping it, packagers' modifications get reviewed by the upstream developers and packagers don't have to duplicate the efforts of other packagers. It complicates version management a bit, but that just boils down to packagers picking a given stable branch of the programme to be packaged for a given distribution release, and ensuring that that branch is maintained for as long as they need it. Which they have to do anyway, but usually with a private distribution branch.