Argh, the starting_version default requires prereqs, so dump_config is too soon to fetch it

    Revert "starting_version now always has a value"

    This reverts commit a545875b9088e29d6e785e3fbc55b6a5b3031092.
Dist-Zilla-Plugin-OnlyCorePrereqs-0.016

          - fix fatal error when [MetaConfig] is used and starting_version is
            not specified (from 0.015)