Comment 12 for bug 1453738

Same issue here.
Fresh ubuntu 15.04 install
choose encrypt disk (bug exist also without full disk encryption, I have also test it, same issue)
choose encrypt home dir
choose LVM
=> auth is requeted for disk encryption (normal), but after also for cryptswap
terminals command regulary prompt :
"Please enter passphrase for disk ubuntu--vg-swap_1 (cryptswap1) on none!"

annoying is that sometime, it prompt on background and "lock" the boot process, waiting to enter anything
to unlock =>hit ESC to show boot info, you can see the
"Please enter passphrase for disk ubuntu--vg-swap_1 (cryptswap1) on none!"
=> hit enter, the boot continue, and you arrive on login.