When updating using packages, there are many different possible expectations:
1) Some admins expect ownCloud to go back to normal mode directly (unattended update)
2) Some admins expect ownCloud to stay in maintenance mode (current behavior)
3) Some admins might want to be able to review changes without users being able to log in or sync: single user mode
How about adding a config.php switch for admins to decide how ownCloud behaves after a successful "occ upgrade" ran ?
The config switch could be called something like "mode_after_update" with values like "normal", "maintenance" or "singleuser".
This also has the advantage of not requiring any changes or configurability inside the post-install scripts of packages.
What do you think ?