Be more careful about ComponentId versus UnitId.
Two big ideas: * @--dependency@ takes a ComponentId, not UnitId. I used to think it should be a UnitId but it is now clear that you want to finger the indefinite unit id, which can be uniquely identified with a ComponentId * When hashing for an InstalledPackageId in new-build, we should produce a ComponentId, not a UnitId. While cleaning up the results, for any codepaths which we don't plan on implementing Backpack (Distribution.Client.Install, I'm looking at you), just coerce ComponentId into UnitIds as necessary. Signed-off-by: Edward Z. Yang <email@example.com>