Payout related vops are handled with current block timestamp instead of head block time (the most likely cause of it working like that in 0.23 is that such date was taken from API call that supplemented it with also head block time, but since it was already past last block processing, its head block time was one block further compared to when operation was actually taking place).
Replaced 1990-01-01 with 1970-01-01 (minimum timestamp) as default in various places where it indicates 'not set' state.
Also fixed:
Typo in fork rewind code (there is no hive_posts_data).
Removed unused last_payout column from hive_posts (the related data was taken from payout_at).