Description:
Hot-plug a virtio console device with specified port on config level, then restart domain twice, finally, the port associated with that console device  changed.

How producible:
Always

Product version:
# rpm -q libvirt
libvirt-1.1.1-29.el7.x86_64

Steps:
1. prepare the following xml.
#cat console.xml
<console type='pty'>
<target type='virtio' port='5'/>
</console>

2. hotplug with option config with the above xml
# virsh attach-device demo console.xml --config
Device attached successfully

3. check the port of the hotpluged device
# virsh dumpxml demo --inactive | grep console -a6
      
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <console type='pty'>
      <target type='virtio' port='5'/>
    </console>

4. Restart domain twice
# virsh destroy demo; virsh start demo
Domain demo destroyed

Domain demo started

# virsh destroy demo; virsh start demo
Domain demo destroyed

Domain demo started

5. check the port of the hotpluged device again
# virsh dumpxml demo | grep console -a6
  
    <console type='pty' tty='/dev/pts/2'>
      <source path='/dev/pts/2'/>
      <target type='serial' port='0'/>
      <alias name='serial0'/>
    </console>
    <console type='pty'>
      <source path='/dev/pts/3'/>
      <target type='virtio' port='1'/>
      <alias name='console1'/>
    </console>

Actual Results:
in step 5: The port of the hotpluged device changed to 1

Expected Results:
in step 5: The port should keep same with the value defined in console.xml and not changed.

Additional Info:
If libvirt support to assign a specified port on virtio console, should fix it,