without the py-libvirt i get

$ virt-convert --help
Traceback (most recent call last):
  File "/usr/bin/virt-convert", line 30, in <module>
    import virtinst.cli as cli
  File "/usr/lib/python2.7/site-packages/virtinst/__init__.py", line 35, in <module>
    import Storage
  File "/usr/lib/python2.7/site-packages/virtinst/Storage.py", line 53, in <module>
    import libvirt
ImportError: No module named libvirt