git bisect is unsure, but one of these commits seems to have
completely broken virtio-serial.

  There are only 'skip'ped commits left to test.
  The first bad commit could be any of:
  0399a3819b27083ba69b88a9baa9025facab85bd
  2ef66625f3a8978dcbbad773e6813f747971381e
  We cannot bisect more!

Anyhow, the error is:

hw/char/virtio-console.c:132:virtconsole_realize: Object 0x7f85482fb8a0 is not an instance of type virtconsole

The full log including command line is attached.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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http://libguestfs.org/virt-v2v