Bug when adding new virtual disk and changing "Device on virtual system" param

When adding a new drive to a Xen VM, if the "Device on virtual system" is changed from the default, the fstab entry is created incorrectly.

For example I changed the field from /dev/sda3 to /dev/sdb1

The disk was created and attached correctly as sdb1, but the fstab entry was created as sda3, resulting in the error: Creating virtual disk on /dev/Xen/www5.sdb1 .. .. creation failed : Failed to mount /dev/sda3 on /backups : mount: special device /dev/sda3 does not exist

Changing /etc/fstab and running 'mount -a' fixed the problem.