Description of problem:

The Cirros 0.3.1 disk image from:
http://download.cirros-cloud.net/0.3.1/cirros-0.3.1-x86_64-disk.img
cannot be inspected very fully by libguestfs.  (The old version 0.3.0
worked much better).  There is no version number or icon.

$ virt-inspector -a cirros-0.3.1-x86_64-disk.img 
<?xml version="1.0"?>
<operatingsystems>
  <operatingsystem>
    <root>/dev/sda1</root>
    <name>linux</name>
    <major_version>0</major_version>
    <minor_version>0</minor_version>
    <hostname>cirros</hostname>
    <format>installed</format>
    <mountpoints>
      <mountpoint dev="/dev/sda1">/</mountpoint>
    </mountpoints>
    <filesystems>
      <filesystem dev="/dev/sda1">
        <type>ext3</type>
        <label>cirros-rootfs</label>
        <uuid>74251bb8-3a28-4a46-9a78-064497b26b9d</uuid>
      </filesystem>
    </filesystems>
    <applications/>
  </operatingsystem>
</operatingsystems>


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

libguestfs-1.25.18-1.fc21.x86_64

How reproducible:

100%

Steps to Reproduce:
1. Download the disk image above.
2. Run virt-inspector -a on the disk image.

Additional info:

This matters a lot because Openstack users frequently use these
as test images.

Compare the output to the 0.3.0 image which was much more
complete:

virt-inspector -a cirros-0.3.0-x86_64-disk.img 
<?xml version="1.0"?>
<operatingsystems>
  <operatingsystem>
    <root>/dev/sda1</root>
    <name>linux</name>
    <distro>cirros</distro>
    <product_name>2011.08</product_name>
    <major_version>2011</major_version>
    <minor_version>8</minor_version>
    <hostname>cirros</hostname>
    <format>installed</format>
    <mountpoints>
      <mountpoint dev="/dev/sda1">/</mountpoint>
    </mountpoints>
    <filesystems>
      <filesystem dev="/dev/sda1">
        <type>ext3</type>
        <label>cirros-rootfs</label>
        <uuid>0e4e199b-d6fe-4869-8897-681fffd48f76</uuid>
      </filesystem>
    </filesystems>
    <applications/>
    <icon>iVBORw0KGgoAAAANSUhEUgAAAMUAAABpAQAAAACindrIAAABdklEQVRIie3Uv0sDMRQH8Fc6
dBJXh4Kb4OYiOAiCk4P/gOhmwUEOcVAQvJ6ODjqJKP4Bzi694eiPTfBPMOgJgk7lqEJzEJOv
ydX+EpR6oQ7ScOS4+/Dy4CUvhG9GTCMZyX+VGtGCeSuiTEyUG1aeKqL2DwmUAc9GPIRtEQCD
goUok+lzcODFJEsvqaoTU5HyRNkDIq+WhX6GsguSQzYBH7KCfWErIoKoA1sQrhKurfAQXG9K
iKaQvGIrqeoWk4fHDGgc2YFjUog+L3UVRlyo1kfVSsxZllVNpjuipEcsRB9jX3iaTIYw6REL
SVMdfREVc49ePGmupjnK2K32Qx4PWAfeTfMiCntjtGwmLc7RuYFa4oYdkf0yQbvsYvp55u3m
6nztdLnRFee+wpzSHXN85rCVS6dfjksPbNtnY4wFG71SDhwtOsYNWLD3VZLVZoPVoLuamirs
XJ8tFpZeb49O5g/zTz01kMncbl4MJHEyN35R0ZH8jXwAq+PI5rqGmGAAAAAASUVORK5CYII=</icon>
  </operatingsystem>
</operatingsystems>