Much simpler calculate_related_by_type.
Much simpler calculate_related_by_type.

--HG--
extra : rebase_source : 88816a1085fcefcbe39edb49b22b174ac912c931

nanaya/moebooru,euank/moebooru-thin,euank/moebooru-thin,nanaya/moebooru,euank/moebooru-thin,moebooru/moebooru,moebooru/moebooru,moebooru/moebooru,euank/moebooru-thin,nanaya/moebooru,nanaya/moebooru,moebooru/moebooru,moebooru/moebooru,nanaya/moebooru,euank/moebooru-thin