Preserve /home directory across OS upgrades

[ideaship]

It seems unlikely that a NOS user would want an operating system upgrade to blow away the content of /home for them. For instance, it can be a rather unpleasant surprise if the home directories of their additional users (already preserved in /etc/passwd etc.) are suddenly gone.

There is a risk that the combined size of /home becomes too big for our backup/restore procedure. Something to consider.

[KanjiMonster]

If users want to have their home directory backed up, they can already enable this via /etc/default/user-backup.txt.

And as you said, there is the risk that it becomes too big, which can happen quite easily since we need to store the backup in the ramdisk in addition to the installer.