When trying to restart the VM, it errors out with:

Erreur lors du démarrage du domaine: (domain_definition):61: Unescaped '<' not allowed in attributes values
    <graphics type='spice' autoport='yes' listen='<gi.overrides.Gtk.TreeModelRow object at 0x3c23a90>'>
--------------------------------------------------^

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 91, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 127, in tmpcb
    callback(*args, **kwargs)
  File "/usr/share/virt-manager/virtManager/domain.py", line 1355, in startup
    self._backend.create()
  File "/usr/lib64/python2.7/site-packages/libvirt.py", line 708, in create
    if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self)
libvirtError: (domain_definition):61: Unescaped '<' not allowed in attributes values
    <graphics type='spice' autoport='yes' listen='<gi.overrides.Gtk.TreeModelRow object at 0x3c23a90>'>
--------------------------------------------------^

However virt-manager says the VM is running, but the context menu has a 'start VM' option.

I suspect this is fixed already by commit 932e6e00bb08647800a62e59f61c8adee9c5de59
Author: Cole Robinson <crobinso>
Date:   Thu Apr 3 10:53:54 2014 -0400

    details: Fix changing graphics type (bz 1083903)
    
    And clean up the API usage to avoid these types of issues in the future.

but I could not test (and the bug # is wrong so I can't check if the symptoms are the same :(