Description of problem:
When attempting to list available releases after attaching a RHEL subscription, this traceback is thrown when using a proxy, but works fine when not using a proxy.

[root@jsefler-rhel6 ~]# tail -f /var/log/rhsm/rhsm.log
2016-12-01 17:35:53,369 [DEBUG] subscription-manager:11858:MainThread @connection.py:309 - Loading CA certificate: '/etc/pki/entitlement/1595989299943042860.pem'
2016-12-01 17:35:53,370 [DEBUG] subscription-manager:11858:MainThread @connection.py:281 - Using proxy: auto-services.usersys.redhat.com:3128
2016-12-01 17:35:53,370 [ERROR] subscription-manager:11858:MainThread @managercli.py:177 - exception caught in subscription-manager
2016-12-01 17:35:53,370 [ERROR] subscription-manager:11858:MainThread @managercli.py:178 - 'ContentConnection' object has no attribute 'proxy_host'
Traceback (most recent call last):
  File "/usr/sbin/subscription-manager", line 81, in <module>
    sys.exit(abs(main() or 0))
  File "/usr/sbin/subscription-manager", line 72, in main
    return managercli.ManagerCLI().main()
  File "/usr/lib/python2.6/site-packages/subscription_manager/managercli.py", line 2768, in main
    return CLI.main(self)
  File "/usr/lib/python2.6/site-packages/subscription_manager/cli.py", line 160, in main
    return cmd.main()
  File "/usr/lib/python2.6/site-packages/subscription_manager/managercli.py", line 537, in main
    return_code = self._do_command()
  File "/usr/lib/python2.6/site-packages/subscription_manager/managercli.py", line 1458, in _do_command
    releases = self.release_backend.get_releases()
  File "/usr/lib/python2.6/site-packages/subscription_manager/release.py", line 48, in get_releases
    return provider.get_releases()
  File "/usr/lib/python2.6/site-packages/subscription_manager/release.py", line 125, in get_releases
    data = self.content_connection.get_versions(listing_path)
  File "/usr/lib64/python2.6/site-packages/rhsm/connection.py", line 327, in get_versions
    results = self._request("GET", handler, body="")
  File "/usr/lib64/python2.6/site-packages/rhsm/connection.py", line 285, in _request
    conn = httplib.HTTPSConnection(self.proxy_host, self.proxy_port, context=context, timeout=self.timeout)
AttributeError: 'ContentConnection' object has no attribute 'proxy_host'




Version-Release number of selected component (if applicable):
[root@jsefler-rhel6 ~]# subscription-manager version
server type: Red Hat Subscription Management
subscription management server: 0.9.51.20-1
subscription management rules: 5.15.1
subscription-manager: 1.18.5-1.el6
python-rhsm: 1.18.5-1.el6


How reproducible:


Steps to Reproduce:
[root@jsefler-rhel6 ~]# subscription-manager config --server.proxy_hostname=auto-services.usersys.redhat.com --server.proxy_port=3129
[root@jsefler-rhel6 ~]# 
[root@jsefler-rhel6 ~]# subscription-manager register --auto-attach --serverurl=subscription.rhsm.stage.redhat.com
Registering to: subscription.rhsm.stage.redhat.com:443/subscription
Username: stage_auto_testuser1
Password: 
The system has been registered with ID: 130d5672-aa98-49e0-91c4-c41692d5c9e6 

Installed Product Current Status:
Product Name: Red Hat Enterprise Linux Server
Status:       Subscribed

[root@jsefler-rhel6 ~]# subscription-manager release --list
'ContentConnection' object has no attribute 'proxy_host'
[root@jsefler-rhel6 ~]# 

BANG! ContentConnection' object has no attribute 'proxy_host'  That was not expected.
Realize that the proxy setting was valid and traffic successfully flowed through the proxy during the registration step.  Now when I remove the proxy confguration, you'll see that the request is successful...

 [root@jsefler-rhel6 ~]# subscription-manager config --server.proxy_hostname="" --server.proxy_port="" --server.proxy_user="" --server.proxy_password=""
[root@jsefler-rhel6 ~]# 
[root@jsefler-rhel6 ~]# subscription-manager release --list
+-------------------------------------------+
          Available Releases
+-------------------------------------------+
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6Server
[root@jsefler-rhel6 ~]# 

WORKS! with no proxy, but....

[root@jsefler-rhel6 ~]# subscription-manager release --list --proxy=auto-services.usersys.redhat.com:3129
'ContentConnection' object has no attribute 'proxy_host'
[root@jsefler-rhel6 ~]# 
[root@jsefler-rhel6 ~]# subscription-manager release --list --proxy=auto-services.usersys.redhat.com:3128 --proxyuser=redhat --proxypassword=redhat
'ContentConnection' object has no attribute 'proxy_host'
[root@jsefler-rhel6 ~]# 

FAILS! with two different proxys (both auth and no-auth)




Actual results:
'ContentConnection' object has no attribute 'proxy_host'

Expected results:
+-------------------------------------------+
          Available Releases
+-------------------------------------------+
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6Server


Additional info: