Comment 2 for bug 1026029

As I going through the source code with essex version as well as the master branch,
I found this problem is still there, both _soft_reboot and _hard_reboot are using none try-except
lookupByName.

Actually, I have made a change in code to deal with `Domain not running' kind of thing in case of
virt_dom is None, and rebuild xml from db; and then all vms are rebooted successfully no matter
there is virt_dom or not.

I wonder if anyone else has encountered the same error as me.