the current code was causing the day to move backwards:
at day 7 hour 23:59, elap is 1
at day 8 hour 0:59, elap is 0
at day 8 hour 1:59, elap is 0
at day 8 hour 2:59, elap is 1
at day 8 hour 3:59, elap is 1
at day 8 hour 4:59, elap is 2
as mentioned in https://github.com/ankitects/anki/pull/416