{autonumber} and {playlist_index} are now integers rather than strings, so {autonumber:02} works and you don't need --autonumber-size.
(Actually, they're "special integers" that get printed to a predefined fixed width if you leave the :02 out; see the _Int_digits class.)
{upload_date} is now a datetime.date, so {upload_date:%b %Y} will format as "Oct 2015" (default is "2015-10-19").
sanitize() gets applied only to string values, not to numeric ones (or dates or lists or...)
f41604b253