Pre-release can't be child of a point release
The current interface doesn't allow us to add prereleases as children of point releases, because the hierarchy can only be 2 levels deep. Should this be changed, or should prereleases for point releases be added as children of the main series? The check for the prerelease being a prerelease, which uses the date of the parent, will not work. OTOH, the interface isn't built to support this amount of nesting.