the idea is to backup on an update call any initramfs that is older than a certain time, lets say 6h or maybe 24hthus not created while upgrading mdadm, udev, usplash, cryptsetup or so together.
How about backuping any initramfs that is older than uptime?
will be in 0.81 update-initramfs.
Good :-) Best regards, Thiemo