Description of problem:
When virt-who work at local libvirt mode, although no changes in host/guests , virt-who still send mapping info to server periodically.

Version-Release number of selected component (if applicable):
virt-who-0.16-7.el6
subscription-manager-1.16.8-7.el6.x86_64
python-rhsm-1.16.6-1.el6.x86_64

How reproducible:
always

Steps to Reproduce:
1. Register system to satellite, make virt-who run at local libvirt mode and enable debug option
[root@dell-pem600-01 ~]# cat /etc/sysconfig/virt-who  | grep -v ^# | grep -v ^$
VIRTWHO_DEBUG=1
2. restart virt-who service and check rhsm.log.
# /etc/init.d/virt-who restart
# tail -f /var/log/rhsm/rhsm.log
3. Make sure no host/guests changes, wait for over 120s.

Actual results:
Virt-who send host/guest mapping info to server side every refresh interval(60s)
========================start virtwho service===============================
2016-03-24 02:01:17,437 [virtwho.main DEBUG] MainProcess(25556):MainThread @virtwho.py:run:231 - Starting infinite loop with 60 seconds interval
2016-03-24 02:01:17,606 [virtwho.env_cmdline DEBUG] Libvirtd-1(25564):MainThread @virt.py:run:358 - Virt backend 'env/cmdline' started
2016-03-24 02:01:17,608 [virtwho.env_cmdline INFO] Libvirtd-1(25564):MainThread @libvirtd.py:_connect:156 - Using libvirt url: ""
2016-03-24 02:01:17,664 [virtwho.env_cmdline DEBUG] Libvirtd-1(25564):MainThread @libvirtd.py:_listDomains:244 - Libvirt domains found: 9bc436d8-20cf-711c-4056-d30f8c709a0f
2016-03-24 02:01:17,664 [virtwho.env_cmdline DEBUG] Libvirtd-1(25564):MainThread @virt.py:enqueue:351 - Report for config "env/cmdline" gathered, putting to queue for sending
2016-03-24 02:01:17,686 [virtwho.main DEBUG] MainProcess(25556):MainThread @subscriptionmanager.py:_connect:121 - Authenticating with certificate: /etc/pki/consumer/cert.pem
2016-03-24 02:01:18,625 [virtwho.main INFO] MainProcess(25556):MainThread @subscriptionmanager.py:sendVirtGuests:147 - Sending update in guests lists for config "env/cmdline": 1 guests found
2016-03-24 02:01:18,625 [virtwho.main DEBUG] MainProcess(25556):MainThread @subscriptionmanager.py:sendVirtGuests:148 - Domain info: [
    {
        "guestId": "9bc436d8-20cf-711c-4056-d30f8c709a0f", 
        "state": 1, 
        "attributes": {
            "active": 1, 
            "hypervisorVersion": "0.12.1", 
            "virtWhoType": "libvirt", 
            "hypervisorType": "QEMU"
        }
    }
]
2016-03-24 02:01:22,366 [virtwho.main DEBUG] MainProcess(25556):MainThread @virtwho.py:send_report:161 - Report for config "env/cmdline" sent

==================After 60s, send mapping info to server====================
2016-03-24 02:02:17,731 [virtwho.env_cmdline DEBUG] Libvirtd-1(25564):MainThread @libvirtd.py:_listDomains:244 - Libvirt domains found: 9bc436d8-20cf-711c-4056-d30f8c709a0f
2016-03-24 02:02:17,732 [virtwho.env_cmdline DEBUG] Libvirtd-1(25564):MainThread @virt.py:enqueue:351 - Report for config "env/cmdline" gathered, putting to queue for sending
2016-03-24 02:02:22,373 [virtwho.main DEBUG] MainProcess(25556):MainThread @subscriptionmanager.py:_connect:121 - Authenticating with certificate: /etc/pki/consumer/cert.pem
2016-03-24 02:02:22,917 [virtwho.main INFO] MainProcess(25556):MainThread @subscriptionmanager.py:sendVirtGuests:147 - Sending update in guests lists for config "env/cmdline": 1 guests found
2016-03-24 02:02:22,918 [virtwho.main DEBUG] MainProcess(25556):MainThread @subscriptionmanager.py:sendVirtGuests:148 - Domain info: [
    {
        "guestId": "9bc436d8-20cf-711c-4056-d30f8c709a0f", 
        "state": 1, 
        "attributes": {
            "active": 1, 
            "hypervisorVersion": "0.12.1", 
            "virtWhoType": "libvirt", 
            "hypervisorType": "QEMU"
        }
    }
]
2016-03-24 02:02:25,042 [virtwho.main DEBUG] MainProcess(25556):MainThread @virtwho.py:send_report:161 - Report for config "env/cmdline" sent

==================After 60s, send mapping info to server====================
2016-03-24 02:03:17,796 [virtwho.env_cmdline DEBUG] Libvirtd-1(25564):MainThread @libvirtd.py:_listDomains:244 - Libvirt domains found: 9bc436d8-20cf-711c-4056-d30f8c709a0f
2016-03-24 02:03:17,796 [virtwho.env_cmdline DEBUG] Libvirtd-1(25564):MainThread @virt.py:enqueue:351 - Report for config "env/cmdline" gathered, putting to queue for sending
2016-03-24 02:03:25,054 [virtwho.main DEBUG] MainProcess(25556):MainThread @subscriptionmanager.py:_connect:121 - Authenticating with certificate: /etc/pki/consumer/cert.pem
2016-03-24 02:03:25,591 [virtwho.main INFO] MainProcess(25556):MainThread @subscriptionmanager.py:sendVirtGuests:147 - Sending update in guests lists for config "env/cmdline": 1 guests found
2016-03-24 02:03:25,592 [virtwho.main DEBUG] MainProcess(25556):MainThread @subscriptionmanager.py:sendVirtGuests:148 - Domain info: [
    {
        "guestId": "9bc436d8-20cf-711c-4056-d30f8c709a0f", 
        "state": 1, 
        "attributes": {
            "active": 1, 
            "hypervisorVersion": "0.12.1", 
            "virtWhoType": "libvirt", 
            "hypervisorType": "QEMU"
        }
    }
]
2016-03-24 02:03:27,878 [virtwho.main DEBUG] MainProcess(25556):MainThread @virtwho.py:send_report:161 - Report for config "env/cmdline" sent
 
Expected results:
Virt-who should show notice info if no host/guest mapping info change in local libvirt mode. for example:
"No change in report gathered using config: "env/cmdline", report not sent."

Additional info: