Description of problem:
power on or power off a guest in vcenter, virt-who failed to send the updated info to SAM, the error message is: 
"Unable to send data: Communication with subscription manager failed with code 500: undefined local variable or method `hypervisor' for #<Class:0x000000059d5828>
"

Version-Release number of selected component (if applicable):
virt-who-0.17-10.el7.noarch
subscription-manager-1.17.15-1.el7.x86_64
python-rhsm-1.17.9-1.el7.x86_64

How reproducible:
always


Steps to Reproduce:
1. register virt-who host to SAM [PASS]

2. configure virt-who for esx mode
[test-esx]
type=esx
server=10.73.3.183
username=Administrator
password=Welcome1!
owner=ACME_Corporation
env=Library

3. start virt-who service [PASS]

4. power off a guest in vCenter, and check the rhsm.log [FAILED]
2016-09-28 14:42:25,737 [virtwho.main DEBUG] MainProcess(13079):MainThread @__main__.py:main:19 - virt-who terminated
2016-09-28 14:42:25,861 [virtwho.init DEBUG] MainProcess(13172):MainThread @executor.py:__init__:65 - Using config named 'test-esx'
2016-09-28 14:42:25,861 [virtwho.init INFO] MainProcess(13172):MainThread @main.py:main:160 - Using configuration "test-esx" ("esx" mode)
2016-09-28 14:42:25,861 [virtwho.init INFO] MainProcess(13172):MainThread @main.py:main:162 - Using reporter_id='dhcp-129-186.nay.redhat.com-35b0b97d746f42e6bb8698e8bb9f26f3'
2016-09-28 14:42:25,863 [virtwho.main DEBUG] MainProcess(13172):MainThread @executor.py:run:171 - Starting infinite loop with 60 seconds interval
2016-09-28 14:42:25,893 [virtwho.test-esx DEBUG] Esx-1(13179):MainThread @virt.py:run:364 - Virt backend 'test-esx' started
2016-09-28 14:42:25,893 [virtwho.test-esx DEBUG] Esx-1(13179):MainThread @esx.py:_prepare:128 - Log into ESX
2016-09-28 14:42:26,134 [virtwho.test-esx DEBUG] Esx-1(13179):MainThread @esx.py:_prepare:131 - Creating ESX event filter
2016-09-28 14:42:26,232 [virtwho.test-esx DEBUG] Esx-1(13179):MainThread @virt.py:enqueue:357 - Report for config "test-esx" gathered, putting to queue for sending
2016-09-28 14:42:26,243 [virtwho.main DEBUG] MainProcess(13172):MainThread @subscriptionmanager.py:_connect:124 - Authenticating with certificate: /etc/pki/consumer/cert.pem
2016-09-28 14:42:26,283 [virtwho.main DEBUG] MainProcess(13172):MainThread @subscriptionmanager.py:hypervisorCheckIn:172 - Checking if server has capability 'hypervisor_async'
2016-09-28 14:42:26,321 [virtwho.main DEBUG] MainProcess(13172):MainThread @subscriptionmanager.py:hypervisorCheckIn:184 - Server does not have 'hypervisors_async' capability
2016-09-28 14:42:26,321 [virtwho.main INFO] MainProcess(13172):MainThread @subscriptionmanager.py:hypervisorCheckIn:195 - Sending update in hosts-to-guests mapping for config "test-esx": 2 hypervisors and 1 guests found
2016-09-28 14:42:26,321 [virtwho.main DEBUG] MainProcess(13172):MainThread @subscriptionmanager.py:hypervisorCheckIn:196 - Host-to-guest mapping: {
    "7a384d56-085c-0e32-c7ad-f7181c3f6ddf": [
        {
            "guestId": "421a578c-1d65-3813-86da-50810d8c83ef", 
            "state": 1, 
            "attributes": {
                "active": 1, 
                "virtWhoType": "esx"
            }
        }
    ], 
    "c74a4d56-677e-dd13-828f-617c5cdf0329": []
}
2016-09-28 14:42:26,642 [virtwho.main DEBUG] MainProcess(13172):MainThread @executor.py:send_report:101 - Report for config "test-esx" sent

========== Start to Power off, check rhsm.log ==========
2016-09-28 14:42:53,443 [virtwho.test-esx DEBUG] Esx-1(13179):MainThread @virt.py:enqueue:357 - Report for config "test-esx" gathered, putting to queue for sending
2016-09-28 14:43:26,676 [virtwho.main DEBUG] MainProcess(13172):MainThread @subscriptionmanager.py:_connect:124 - Authenticating with certificate: /etc/pki/consumer/cert.pem
2016-09-28 14:43:26,717 [virtwho.main DEBUG] MainProcess(13172):MainThread @subscriptionmanager.py:hypervisorCheckIn:172 - Checking if server has capability 'hypervisor_async'
2016-09-28 14:43:26,757 [virtwho.main DEBUG] MainProcess(13172):MainThread @subscriptionmanager.py:hypervisorCheckIn:184 - Server does not have 'hypervisors_async' capability
2016-09-28 14:43:26,757 [virtwho.main INFO] MainProcess(13172):MainThread @subscriptionmanager.py:hypervisorCheckIn:195 - Sending update in hosts-to-guests mapping for config "test-esx": 2 hypervisors and 1 guests found
2016-09-28 14:43:26,757 [virtwho.main DEBUG] MainProcess(13172):MainThread @subscriptionmanager.py:hypervisorCheckIn:196 - Host-to-guest mapping: {
    "7a384d56-085c-0e32-c7ad-f7181c3f6ddf": [
        {
            "guestId": "421a578c-1d65-3813-86da-50810d8c83ef", 
            "state": 5, 
            "attributes": {
                "active": 0, 
                "virtWhoType": "esx"
            }
        }
    ], 
    "c74a4d56-677e-dd13-828f-617c5cdf0329": []
}
2016-09-28 14:43:27,177 [virtwho.main ERROR] MainProcess(13172):MainThread @executor.py:send:143 - Unable to send data: Communication with subscription manager failed with code 500: undefined local variable or method `hypervisor' for #<Class:0x000000059d5828>
2016-09-28 14:43:27,177 [virtwho.main DEBUG] MainProcess(13172):MainThread @executor.py:send_report:108 - Report from "test-esx" failed to sent


========= After 1 minute, check the log again, it's sent successfully====
 2016-09-28 14:43:53,445 [virtwho.test-esx DEBUG] Esx-1(13179):MainThread @virt.py:enqueue:357 - Report for config "test-esx" gathered, putting to queue for sending
2016-09-28 14:44:27,212 [virtwho.main DEBUG] MainProcess(13172):MainThread @subscriptionmanager.py:_connect:124 - Authenticating with certificate: /etc/pki/consumer/cert.pem
2016-09-28 14:44:27,252 [virtwho.main DEBUG] MainProcess(13172):MainThread @subscriptionmanager.py:hypervisorCheckIn:172 - Checking if server has capability 'hypervisor_async'
2016-09-28 14:44:27,290 [virtwho.main DEBUG] MainProcess(13172):MainThread @subscriptionmanager.py:hypervisorCheckIn:184 - Server does not have 'hypervisors_async' capability
2016-09-28 14:44:27,290 [virtwho.main INFO] MainProcess(13172):MainThread @subscriptionmanager.py:hypervisorCheckIn:195 - Sending update in hosts-to-guests mapping for config "test-esx": 2 hypervisors and 1 guests found
2016-09-28 14:44:27,290 [virtwho.main DEBUG] MainProcess(13172):MainThread @subscriptionmanager.py:hypervisorCheckIn:196 - Host-to-guest mapping: {
    "7a384d56-085c-0e32-c7ad-f7181c3f6ddf": [
        {
            "guestId": "421a578c-1d65-3813-86da-50810d8c83ef", 
            "state": 5, 
            "attributes": {
                "active": 0, 
                "virtWhoType": "esx"
            }
        }
    ], 
    "c74a4d56-677e-dd13-828f-617c5cdf0329": []
}
2016-09-28 14:44:27,607 [virtwho.main DEBUG] MainProcess(13172):MainThread @executor.py:send_report:101 - Report for config "test-esx" sent