- new upstream version
    - release number must be high, because of stale version numbers of some of
        the subpackages
    - drop upstreamed patches
    - update the versions of bundled modules
    - shorten the paths in @INC
    - build without DEBUGGING
    - implement compatibility measures for the above two changes, for a short
        transition period
    - provide perl(:MODULE_COMPAT_5.10.0), for that transition period only