(this may be bumped to 2.1 or even made WON't FIX as it is contentious - see
currently, you have to specify the parent version when extending which makes a project stand alone very easily, but has the drawback of being a maintainance problem when you start development on a new version. Tools can help, but it would be nice not to have to rely on them.
One alternative is to allow the parent version to be omitted, and when it is it is assumed you want the latest. The parent is used from the reactor or the universal source directory. IT may also be read from a LATEST in the repository though this is contentious - it may be better to simply fail in that environment and require builds be in a known checkout structure for building individual projects.
This also introduces the need for tool support to populate the version on release and deployment for reproducibility.