Description of problem:

From oneiric onwards, the install CDs provided by Ubuntu show up
as multiple operating systems.  This is because the CD
contains the same filesystem on the whole device (eg. /dev/vda)
and on a partition (/dev/vda1):

><fs> dmesg | grep vda1
[    1.309559]  vda: vda1
><fs> file /dev/vda
# ISO 9660 CD-ROM filesystem data 'Ubuntu-Server 12.04 LTS amd64   ' (bootable)
><fs> file /dev/vda1 
# ISO 9660 CD-ROM filesystem data 'Ubuntu-Server 12.04 LTS amd64   '
><fs> list-filesystems 
/dev/vda1: iso9660
><fs> mount-ro /dev/vda /
><fs> umount /
><fs> mount-ro /dev/vda1 /
><fs> umount /
><fs> vfs-type /dev/vda
iso9660
><fs> vfs-type /dev/vda1
iso9660

Version-Release number of selected component (if applicable):

1.17.8
kernel 3.3.0-0.rc2.git4.1.fc17.x86_64

How reproducible:

100%

Steps to Reproduce:
1. virt-inspector -a ubuntu.iso | grep '<operatingsystem>' | wc -l
  
Actual results:

It displays '1' for Ubuntu < oneiric, and '2' for Ubuntu >= oneiric.

Expected results:

It should display '1'.

Additional info: