This will be needed for database upgrades going forward. For example, an
old session without an update timestamp will not be visible in the index
that will soon be added. But since the UI will switch to that index, it
is paramount that all sessions are part of that.
The session model was built with that in mind, and has the corresponding
"update" logic. However, for that to matter old records first need to be
readded to the database.
