Description of problem:
Config virt-who connect rhevm with proxy, although virt-who can access the rhevm normally with squid proxy, but it failed to send mapping info to SAM server as "no_proxy" configure hasn't taken effect, it will take effect in python-rhsm-1.15.1-1 or newer.

Version-Release number of selected component (if applicable):
Rhev-hypervisor7-7.2-20160302.1
virt-who-0.14-9.el7.noarch
vdsm-4.17.23-0.el7ev.noarch
subscription-manager-1.10.14-10.el7.x86_64
python-rhsm-1.13.2-1.el7.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Register system to SAM
2. Configure virt-who connect with rhevm with proxy.
[root@localhost admin]# cat /etc/sysconfig/virt-who  | grep -v ^# | grep -v ^$
VIRTWHO_DEBUG=1
https_proxy=https://10.73.2.81:3128
no_proxy=samserv.redhat.com
VIRTWHO_RHEVM=1
VIRTWHO_RHEVM_OWNER=ACME_Corporation
VIRTWHO_RHEVM_ENV=Library
VIRTWHO_RHEVM_SERVER=https://10.73.2.65:443
VIRTWHO_RHEVM_USERNAME=admin@internal
VIRTWHO_RHEVM_PASSWORD=redhat
3. Restart virt-who service and check virt-who's log
[root@localhost admin]# service virt-who restart && tail -f /var/log/rhsm/rhsm.log

2016-03-16 02:04:10,989 [INFO]  @virtwho.py:697 - Using configuration "env/cmdline" ("rhevm" mode)
2016-03-16 02:04:10,990 [DEBUG]  @virtwho.py:216 - Starting infinite loop with 3600 seconds interval
2016-03-16 02:04:11,419 [DEBUG]  @subscriptionmanager.py:112 - Authenticating with certificate: /etc/pki/consumer/cert.pem
2016-03-16 02:04:11,463 [ERROR]  @virtwho.py:190 - Error in communication with subscription manager:
Traceback (most recent call last):
  File "/usr/share/virt-who/virtwho.py", line 173, in send
    self._sendGuestAssociation(report)
  File "/usr/share/virt-who/virtwho.py", line 204, in _sendGuestAssociation
    report.config.type)
  File "/usr/share/virt-who/manager/subscriptionmanager/subscriptionmanager.py", line 145, in hypervisorCheckIn
    self._connect(config)
  File "/usr/share/virt-who/manager/subscriptionmanager/subscriptionmanager.py", line 120, in _connect
    if not self.connection.ping()['result']:
  File "/usr/lib64/python2.7/site-packages/rhsm/connection.py", line 705, in ping
    return self.conn.request_get("/status/")
  File "/usr/lib64/python2.7/site-packages/rhsm/connection.py", line 550, in request_get
    return self._request("GET", method)
  File "/usr/lib64/python2.7/site-packages/rhsm/connection.py", line 453, in _request
    conn.request(request_type, handler, body=body, headers=headers)
  File "/usr/lib64/python2.7/httplib.py", line 979, in request
    self._send_request(method, url, body, headers)
  File "/usr/lib64/python2.7/httplib.py", line 1013, in _send_request
    self.endheaders(body)
  File "/usr/lib64/python2.7/site-packages/rhsm/connection.py", line 198, in endheaders
    httpslib.HTTPSConnection.endheaders(self)
  File "/usr/lib64/python2.7/httplib.py", line 975, in endheaders
    self._send_output(message_body)
  File "/usr/lib64/python2.7/httplib.py", line 835, in _send_output
    self.send(msg)
  File "/usr/lib64/python2.7/httplib.py", line 797, in send
    self.connect()
  File "/usr/lib64/python2.7/site-packages/M2Crypto/httpslib.py", line 206, in connect
    raise socket.error, "Proxy connection failed: %d" % code
error: Proxy connection failed: 404

Actual results:
Virt-who can access the rhevm normally with squid proxy, but it failed to send mapping info to satellite server and return 404 error 

Expected results:
rhevh7.2 should use the python-rhsm-1.15.1-1 or newer. Then Virt-who can connect rhevm successfully through proxy and "no_proxy" configure can take effect.

Additional info:
Please see a similar bug on rhel6.8:
https://bugzilla.redhat.com/show_bug.cgi?id=1309611