Lack of a lease (whether mac is given or not) is a normal expected
scenario, since we are already filling in rv with nleases (which is
okay as 0 if there is no lease). There is no need to raise an error.
This fixes:
> virsh # net-dhcp-leases --mac 00:50:56:c0:00:01 default
> error: Failed to get leases info for default
> error: internal error: no lease with matching MAC address: 00:50:56:c0:00:01
Signed-off-by: Nehal J Wani <nehaljw.kkd1@gmail.com> Signed-off-by: Eric Blake <eblake@redhat.com>