release-upgrade needs to address fstab entries for devices that will change names (sda -> xvda)

[Scott Moser]

On Ec2, when the user upgrades from 10.10 to 11.04, or later, from 10.04 to 12.04, the kernel that is installed will change names from /dev/sdX to /dev/xvdX.

If the user has entries in /etc/fstab referring to /dev/sdX, they'll not get those devices mounted on reboot into the new kernel.
Worse, if they do not have 'nobootwait' option for those entries, the wont reboot all the way. On EC2, thats bad as fixing it is possibly impossible.

It seems that it might be best to
 a.) detect this situation
 b.) update entries in fstab that use device names rather than label= or UUID= to use LABEL= or UUID=.

This would have to be thought out though, as there might be cases where the user would explicitly want the /dev/XXX entries.

related bug:
 * bug 684875: Patch to Natty 2.6.37-virtual breaks non-EC2 users
   Comments there by cjwatson about a way to detect this.

[Steve Langasek (vorlon)]

The Precise Pangolin has reached end of life, so this bug will not be fixed for that release