Just to document my verification about VMXML not having special behavior on assignments:

```
>>> import virttest.libvirt_xml
>>> vm1 = virttest.libvirt_xml.VMXML()
>>> vm2 = vm1
>>> vm2 is vm1
True
>>> vm1.set_vm_name('foo')
>>> vm1.vm_name
'foo'
>>> vm2.vm_name
'foo'
```