Comment 39 for bug 953875

This is a lot worse now that systemd actually complains about the missing device and blocks the boot on it for 90s. I just discussed that with Dustin. Summary:

 - This was introduced in https://bazaar.launchpad.net/~ecryptfs/ecryptfs/trunk/revision/776 but can't work (see https://wiki.archlinux.org/index.php/Dm-crypt/Swap_encryption).
 - Fix for future installs: Add offset=1024, to maintain the swap signature and UUID on the underlying hardware device
 - While we are at it: change the obsolete cipher setting to the current cryptsetup default "cipher=aes-xts-plain64"

For upgrades:
Add postinst code to clean up broken installs: find the missing swap partitions and comment them out in crypttab and fstab. We also discussed a possible salvation of swap partitions, running mkswap -U <expected UUID> on them, but IMHO it is unexpected and intrusive to suddenly get a swap partition after having an existing installations for years without one.