Comment 2 for bug 624956

This is still the case in precise and is in fact a double bug: not only is the partition not unmounted on failure, but would the user try again it is mounted again, which could lead to data loss.

The script should first test whether the partition is mounted (and find out where) before trying to mount it. If already mounted, then you need to block it mounted during the update (cd /mount/point comes to mind.)