As someone who runs Ubuntu on a laptop with a dead battery, that's somewhat unfortunate.
> The mail client Evolution may delete folders and their contents as they are renamed or moved around in IMAP (and IMAP+) accounts. It is recommended to copy folders and contents before attempting to move or rename them. (957341)
Ouch! I'm surprised a bug that big with a default application wasn't a release blocker.
I'd guess from the phrasing that suspend-to-disk can still be enabled, it just isn't by default.
$> sudo pm-hibernate
Then turn it back on. If everything works ok, you can permanently add it back to the system menu with these scripts:
https://github.com/repos-ubuntu/tweaks
Need two files:
https://github.com/repos-ubuntu/tweaks/blob/master/reenable-...
https://github.com/repos-ubuntu/tweaks/blob/master/reenable-...
Instructions and links to more detailed instructions in the .sh comments.
'pmi action hibernate'