Comment 3 for bug 209515

If the PPA user wants to have say bzr 1.2 and 1.3 available for an extended period of time, then giving them different names and having a metapackage point at just one of them is the standard way to do it.

However, for handling short transitions from one version of a related package to another the PPA approach seems worse than what is done in a standalone archive managed by apt-ftparchive.