Description of problem:
When the guest' image file is not existed, i think clone should not succeed."clone" button should be disabled; and when i renamed a guest' image file when the guest is running, then clone it, there are also problems.

Version-Release number of selected component (if applicable):
kernel-2.6.32-207.el6.x86_64
libvirt-0.9.4-19.el6.x86_64
virt-manager-0.9.0-7.el6.x86_64
python-virtinst-0.600.0-5.el6.noarch
qemu-kvm-0.12.1.2-2.196.el6.x86_64

How reproducible:
always

Steps to Reproduce:
1. Assume there is a shutdown guest. Rename its image file or remove it from disk.
2. #virt-manager -> (select the guest, and right click)clone ; Clone will be successful. (Not expected. I think it should not be successful according to step3.)
3. use command:
   ## virt-clone -o a -n b -f /var/lib/libvirt/images/b.img
   ERROR    Could not determine original disk information: Disk '/var/lib/libvirt/images/a.img' does not exist.

4. Assume there is a running guest. Rename its image file or remove it from disk.
5. use virt-manager to clone it, and virt-manager will not allow you to clone it.(Expected)
6. Pause the running guest, and virt-manager will allow you to clone it. (Not Expected. Because image file not existed.)
7. Resume the paused guest, and virt-manager will allow you to clone it. (Not Expected. Because image file not existed.)
8. Rename the image file to its original name. Use virt-manager to clone it, and virt-manager will allow you to clone it.(Not refresh, the image file is already existed.)
9. And use command: The result will always be the following if its image file is renamed or removed from disk.
   ## virt-clone -o a -n b -f /var/lib/libvirt/images/b.img
   ERROR    Could not determine original disk information: Disk '/var/lib/libvirt/images/a.img' does not exist.

  

Actual results:
See above.

Expected results:
See above.

Additional info: