Update to latest HEAD.
    
    - Use makecache systemd timer on f20, maybe use it on f19 too?
    - installonlypkgs: remove unneeded provides, add "installonlypkg(kernel)"
    - docs: Suggest "--" when using "-<pkg>" to exclude packages. BZ 1026598.
    - applydeltarpm: turn fork() failure to MiscError. BZ 1028334.