Description of problem:
When sort by ID, get AttributeError of 'vmmConnection' object.

Version-Release number of selected component (if applicable):
virt-manager-0.6.1-15.el5
libvirt-0.8.2.24.el5
python-virtinst-0.400.3-13.el5
kvm-83-243.el5

# uname -a
Linux wjw.redhat.com 2.6.18-294.el5 #1 SMP Tue Oct 25 16:30:40 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux

How reproducible:
always

Steps to Reproduce:
1). Launch virt-manager and active local qemu connection. # virt-manager --debug --no-fork
2). Make sure some guests running. # virsh list --all
Id Name State
----------------------------------
2 4u9-1 running
3 4u9 running

3). Click ID table on the main virtual machine manager screen.
4). Virtual machine will be ordered by ID, but there is AttributeError with 'vmmConnection' object.
Traceback (most recent call last):
File "/usr/share/virt-manager/virtManager/manager.py", line 968, in vmlist_domain_id_sorter
return cmp(model.get_value(iter1, ROW_HANDLE).get_id(), model.get_value(iter2, ROW_HANDLE).get_id())
AttributeError: 'vmmConnection' object has no attribute 'get_id'

Actual results:
As above.

Expected results:
The ID sort function should remove 'vmmConnection' object and only sort the guest ID.