The description of the list command seemed to suggest that it could
take a set of domains as an argument, which is not correct in the
current HEAD.  If virsh list is intended to take a list of domains,
then this patch should be NAK'd and a bug opened against virsh list.

Reported by hachi on #virt

v2:

Change language to include transient domains

Osier pointed out that transient domains are not defined, so what I
had originally proposed wasn't quite correct.