I don't see how it can manage, e.g. a development version of a postrelease, with an SVN rev or date stamp on it. Such versions might not be found on PyPI or on RPMs, but would be needed in development.
I had thought the use cases for dev- and post- releases *was* to use an SVN (or other SCC systems') rev or a date stamp, thus meaning there would be no need for handling "a development version of a post-release".
Perhaps I'm just not seeing it though, I haven't been involved with a project that does post-releases. Can someone describe a concrete example?