If redefining a domain in the xen xm driver, we unconditionally set the
domain ID to -1. This can make a running domain appear inactive, and
really confuse things. Just drop the offending code, since virGetDomain
already sets the ID to -1 if required.
Fix pointed out by Dan Berrange, more info can be found at
https://bugzilla.redhat.com/show_bug.cgi?id=508278
Thanks,
Cole