Description of problem:


Version-Release number of selected component (if applicable):
1. Keep the lease during VM running
2. If the status file not exist, it should be treat as no lease yet, but filter with a specific MAC address should report error.

How reproducible:
libvirt-1.2.8-16.el7_1.2.x86_64 

Steps to Reproduce:
Issue 1:
1. Start a VM, which using the 'default' network:
# virsh dumpxml virt-tests-vm1
...
    <interface type='network'>
      <mac address='52:54:00:11:b5:47'/>
      <source network='default' bridge='virbr0'/>
      <target dev='vnet0'/>
      <model type='virtio'/>
      <alias name='net0'/>
...
2. Check the dhcp leases info
# virsh net-dhcp-leases default
 Expiry Time          MAC address        Protocol  IP address       Hostname        Client ID or DUID
-------------------------------------------------------------------------------------------------------------------
 2015-03-20 12:37:17  52:54:00:11:b5:47  ipv4      192.168.122.107/24       vm2-ydu1   
     -
# cat /var/lib/libvirt/dnsmasq/virbr0.status 
[
    {
        "ip-address": "192.168.122.107",
        "mac-address": "52:54:00:11:b5:47",
        "hostname": "vm2-ydu1",
        "expiry-time": 1426826237
    }
]

Then, keep the VM running and after the time count down to '2015-03-20 12:37:17', and run the command again, there's no lease info return.
But the VM do have the lease, and the 'default.leases' file keep update the expiry time(The value in this example is not update yet)
# cat /var/lib/libvirt/dnsmasq/default.leases
1426750046 52:54:00:11:b5:47 192.168.122.107 vm2-ydu1 *

and the status file not update automatically.

Issue 2:
1. Create/Define start a network(Using the 'default' network a temple)
Just edit network name, bridge name and ip/dhcp range
# virsh net-dumpxml virttestnet
<network>
  <name>virttestnet</name>
  <uuid>34ff4355-ccb8-4a77-98f6-48a0efe477c8</uuid>
  <forward mode='nat'>
    <nat>
      <port start='1024' end='65533'/>
    </nat>
  </forward>
  <bridge name='virbr2' stp='on' delay='0'/>
  <mac address='52:54:00:26:33:12'/>
  <domain name='virttestnet'/>
  <ip address='192.168.110.1' netmask='255.255.255.0'>
    <dhcp>
      <range start='192.168.110.2' end='192.168.110.254'/>
    </dhcp>
  </ip>
</network>

As no VM use this network, so the dhcp lease should be empty, and not 'virbr2.status' file create.
There' an error in libvirtd.log:
Mar 23 10:16:20 localhost journal: Failed to open file '/var/lib/libvirt/dnsmasq/virbr2.status': No such file or directory 


2. Run command to check the dhcp leases
# virsh net-dhcp-leases virttestnet
 Expiry Time          MAC address        Protocol  IP address       Hostname        Client ID or DUID
-------------------------------------------------------------------------------------------------------------------

3. Run it again by using an invalid MAC address(Expect command fail)
# virsh  net-dhcp-leases virttestnet --mac 0000000000000000000000000
 Expiry Time          MAC address        Protocol  IP address       Hostname        Client ID or DUID
-------------------------------------------------------------------------------------------------------------------

# echo $?
0


Actual results:


Expected results:
1. command return leases info if there's active interfaces

2. # virsh  net-dhcp-leases virttestnet --mac 0000000000000000000000000
error: Failed to get leases info for virttestnet
error: internal error: no lease with matching MAC address: 0000000000000000000000000

Additional info: