Why 'cobbler signature update' fails ?

Issue

# cobbler signature update
task started: 2016-01-17_170515_sigupdate
task started (id=Updating Signatures, time=Sun Jan 17 17:05:15 2016)
Exception occured: <class 'urlgrabber.grabber.URLGrabError'>
Exception value: [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found"
Exception Info:
  File "/usr/lib/python2.6/site-packages/cobbler/api.py", line 601, in signature_update
    response = urlgrabber.grabber.urlopen(self.settings().signature_url, proxies=proxies)
   File "/usr/lib/python2.6/site-packages/urlgrabber/grabber.py", line 628, in urlopen
    return default_grabber.urlopen(url, **kwargs)
   File "/usr/lib/python2.6/site-packages/urlgrabber/grabber.py", line 926, in urlopen
    return self._retry(opts, retryfunc, url)
   File "/usr/lib/python2.6/site-packages/urlgrabber/grabber.py", line 886, in _retry
    r = apply(func, (opts,) + args, {})
   File "/usr/lib/python2.6/site-packages/urlgrabber/grabber.py", line 925, in retryfunc
    return PyCurlFileObject(url, filename=None, opts=opts)
   File "/usr/lib/python2.6/site-packages/urlgrabber/grabber.py", line 1066, in __init__
    self._do_open()
   File "/usr/lib/python2.6/site-packages/urlgrabber/grabber.py", line 1360, in _do_open
    self._do_grab()
   File "/usr/lib/python2.6/site-packages/urlgrabber/grabber.py", line 1490, in _do_grab
    self._do_perform()
   File "/usr/lib/python2.6/site-packages/urlgrabber/grabber.py", line 1347, in _do_perform
    raise err

!!! TASK FAILED !!!

• installed the recommended patches and facing this issue.