Description of problem: When an rpm repository is created and a relative url is not given, the derived url is an absolute path.


Version-Release number of selected component (if applicable): master


How reproducible: always


Steps to Reproduce:
1. pulp-admin rpm repo create --repo-id=zoo --feed=http://repos.fedorapeople.org/repos/pulp/pulp/demo_repos/zoo/
2. pulp-admin rpm repo list --details

Actual results:
...
Distributors:        
  Auto Publish:        True
  Config:              
    Http:         False
    Https:        True
    Relative URL: /repos/pulp/pulp/demo_repos/zoo/
  Distributor Type Id: yum_distributor
  Id:                  yum_distributor
  Last Publish:        None
  Repo Id:             zoo
  Scheduled Publishes: 


Expected results: the relative url should be 'repos/pulp/pulp/demo_repos/zoo/'


Additional info: possibly related to https://bugzilla.redhat.com/show_bug.cgi?id=976333