inspect-os in RHEL6 returns nothing on img based XFS filesystem

Issue

RHEL6 guestfish is not able to get the OS type in VM with xfs filesystems.

inspect-os failed with

mount: wrong fs type, bad option, bad superblock on /dev/sda1,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

guestfsd: error: /dev/sda1 on / (options: 'ro'): mount: wrong fs type, bad option, bad superblock on /dev/sda1,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try