- Latest head.
    - Add filtering requires code for createrepo.
    - Add installed_by/changed_by yumdb values.
    - Tweak output for install/reinstall/downgrade callbacks.
    - Add plugin hooks for pre/post verifytrans.
    - Deal with local pkgs. which only obsolete.
    - No chain removals on downgrade.
    - Bunch of speedups for "list installed blah", and "remove blah".