Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=1907864

Description of problem: Repository enable failed on http-proxy configured setup.

Version-Release number of selected component (if applicable):
6.9 Snap 5

How reproducible:
always

Steps to Reproduce:
1. Install satellite on ipv6 setup.
2. Configure http-proxy.
3. Add the latest subscription.
4. Enable the RedHat repository, Repository enables failed with 404 error.

Dec 15 06:39:50 qesat68 pulp: kombu.transport.qpid:INFO: Connected to qpid with SASL mechanism ANONYMOUS
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920) Exception adding importer to repo [695ada71-9d1e-482b-afe6-7443f21f6443]; the repo will be deleted
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920) Traceback (most recent call last):
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)   File "/usr/lib/python2.7/site-packages/pulp/server/controllers/repository.py", line 422, in create_repo
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)     importer_controller.set_importer(repo_id, importer_type_id, importer_repo_plugin_config)
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)   File "/usr/lib/python2.7/site-packages/celery/local.py", line 191, in __call__
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)     return self._get_current_object()(*a, **kw)
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)   File "/usr/lib/python2.7/site-packages/pulp/server/async/tasks.py", line 688, in __call__
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)     return super(Task, self).__call__(*args, **kwargs)
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)   File "/usr/lib/python2.7/site-packages/pulp/server/async/tasks.py", line 110, in __call__
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)     return super(PulpTask, self).__call__(*args, **kwargs)
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)   File "/usr/lib/python2.7/site-packages/celery/app/task.py", line 379, in __call__
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)     return self.run(*args, **kwargs)
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)   File "/usr/lib/python2.7/site-packages/pulp/server/controllers/importer.py", line 99, in set_importer
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)     validate_importer_config(repo, importer_type_id, clean_config)
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)   File "/usr/lib/python2.7/site-packages/pulp/server/controllers/importer.py", line 177, in validate_importer_config
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920)     raise exceptions.PulpDataException(message)
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920) PulpDataException: Configuration errors:
Dec 15 06:39:50 qesat68 pulp: pulp.server.controllers.repository:ERROR: (11461-97920) The configuration parameter <proxy_username> requires the <proxy_password> parameter to also be set.
Dec 15 06:39:50 qesat68 pulp: pulp.server.webservices.middleware.exception:INFO: (11461-97920) Configuration errors:
Dec 15 06:39:50 qesat68 pulp: pulp.server.webservices.middleware.exception:INFO: (11461-97920) The configuration parameter <proxy_username> requires the <proxy_password> parameter to also be set.
</p>

*Actual results:*
repository enable failed with a configuration error.

*Expected results:*
repository enable should work

*Additional info:*'