virsh edit xml changes are lost

Question

virsh edit xml changes are lost

Using 'virsh edit ' command I tried to edit the xml file for a specific guest . I wanted to add serial ttyS0 for the guest machine, but I found that after using virsh edit then inserted below lines just before '' keyword I saved the file using ':wq!' (vi editor style) and booted the guest again but there is no impact. Also the changes I made in the xml does nt stay , it is lost immediately , I am editing the file with root as the user.

    <serial type='pty'>
        <target port='0'/>
    </serial>
    <console type='pty'>
    <target type='serial' port='0'/>
    </console>
  </devices>
</domain>

'Devices' and 'console' were already present in the file at the last . I inserted the code before 'devices' as display above.