Satellite 6: Why does enabling Red Hat repositories fail with "Pulp exception occurred: AuthenticationFailed" ?

Issue

• Trying to enable repositories. Activity wheel is spinning and nothing seems to be happening.

Content > Red Hat Repositories -> RPMs tab > Red Hat Enterprise Linux Server >  Red Hat Enterprise Linux 7 Server (RPMs) 

• /var/log/messages

Oct 28 10:58:23 satellite pulp: pulp.server.webservices.middleware.exception:ERROR:   File "/usr/lib/python2.6/site-packages/pulp/server/webservices/controllers/decorators.py", line 192, in _auth_decorator
Oct 28 10:58:23 satellite pulp: pulp.server.webservices.middleware.exception:ERROR:     userid, is_consumer = authenticate_user()
Oct 28 10:58:23 satellite pulp: pulp.server.webservices.middleware.exception:ERROR:   File "/usr/lib/python2.6/site-packages/pulp/server/webservices/controllers/decorators.py", line 118, in oauth_authentication
Oct 28 10:58:23 satellite pulp: pulp.server.webservices.middleware.exception:ERROR:     raise AuthenticationFailed(auth_utils.CODE_OAUTH)
Oct 28 10:58:23 satellite pulp: pulp.server.webservices.middleware.exception:ERROR: AuthenticationFailed: Pulp exception occurred: AuthenticationFailed

• /var/log/foreman/production.log

[ERROR 2014-10-28 10:58:23 pulp_rest  #2498] RestClient.post "https://satellite1.example.com/pulp/api/v2/repositories/", 24778 byte(s) length, "Accept"=>"*/*; q=0.5, application/xml", "Accept-Encoding"=>"gzip, deflate", "Authorization"=>"OAuth oauth_body_hash=\"2jmj7l5rSw0yVb%2FvlWAYkK%2FYBwk%3D\", oauth_consumer_key=\"katello\", oauth_nonce=\"QMP6qkIdZR9maP34zDdp0uLJsU6JsG4VTVAMZts97c\", oauth_signature=\"TvqVY40lqBvJAOT85xK3An94bvI%3D\", oauth_signature_method=\"HMAC-SHA1\", oauth_timestamp=\"1414490303\", oauth_version=\"1.0\"", "Content-Length"=>"24778", "accept"=>"application/json", "content_type"=>"application/json", "pulp-user"=>"test-b0dbbbb3"
 | \n# => 401 Unauthorized | application/json 366 bytes