https://bugzilla.redhat.com/show_bug.cgi?id=1006864
Commit 38ab1225 changed the default value of ret from true to false but
forgot to set ret = true when job is NONE. Thus, virsh domjobinfo
returned 1 when there was no job running for a domain but it used to
(and should) return 0 in this case.
(cherry picked from commit f084caae7c5db8ae03e7fafce164c73f65681843)