spacewalk-repo-sync fails with traceback "[Errno 256] No more mirrors to try".

Issue

• Trying to sync channel with Fedora epel repository using spacewalk-repo-sync.
• spacewalk-repo-sync fails with traceback

Traceback (most recent call last)
  File "/usr/bin/spacewalk-repo-sync", line 72, in <module>
    sys.exit(abs(main() or 0))
  File "/usr/bin/spacewalk-repo-sync", line 66, in main
    sync.main()
  File "/usr/share/rhn/satellite_tools/reposync.py", line 103, in main
    self.import_packages(plugin, url)
  File "/usr/share/rhn/satellite_tools/reposync.py", line 135, in import_packages
    packages = plug.list_packages()
  File "/usr/share/rhn/satellite_tools/repo_plugins/yum_src.py", line 75, in list_packages
    sack.populate(repo, 'metadata', None, 0)
  File "/usr/lib/python2.6/site-packages/yum/yumRepo.py", line 173, in populate
    db_fn = repo._retrieveMD(mydbtype)
  File "/usr/lib/python2.6/site-packages/yum/yumRepo.py", line 1608, in _retrieveMD
    size=thisdata.size)
  File "/usr/lib/python2.6/site-packages/yum/yumRepo.py", line 835, in _getFile
    raise Errors.NoMoreMirrorsRepoError, errstr
NoMoreMirrorsRepoError failure repodata/cb051595ca4dc2414d6c755142f0493932056f4a520b1c766837fa02cd469178-primary.sqlite.bz2 from test-rhel6-x86_64-epel [Errno 256] No more mirrors to try.