ZIP 308: Migration txns SHOULD only be sent if the timestamp of the block used to trigger sending a batch is more recent than 3 hours ago according to the node's adjusted clock.
ZIP 308: Migration txns SHOULD only be sent if the timestamp of the block used to trigger sending a batch is more recent than 3 hours ago according to the node's adjusted clock.

Signed-off-by: Daira Hopwood <cd7d43d5556a38ce626d53826fddc46adc597539@jacaranda.org>

zcash/zips,zcash/zips,zcash/zips,zcash/zips