I ran into a bug when deploying this + Samba4 for Previous Versions to a Windows 7 client - all of the snapshots were appearing as 'Tomorrow'. It seems that Windows 7, at least, expects the date given to be in UTC. As I'm in UTC+8, this made all of the dates 8h ahead!
Just added the --utc flag to the date code there, and Windows 7 now correctly gives the date. This shouldn't affect anything else, since cron takes care of scheduling. UTC is also better idea to be storing the snapshot date in, as well.
Set the snapshots to use UTC time, which makes the date/time display …
…correctly in Windows 7 Previous Versions.
@hawkowl, good idea, merged, thanks.
However, to preserve default behavior for point releases, this change should be wrapped with a program option per zfsonlinux/zfs-auto-snapshot#19.