Trying to roll gn using tools/gn/bin/roll_gn.py script, the "wait" commands fails with a 404 error:

$ tools/gn/bin/roll_gn.py wait
Already on 'build_gn_465181'
Checking build
Traceback (most recent call last):
  File "tools/gn/bin/roll_gn.py", line 468, in <module>
    sys.exit(roller.Roll())
  File "tools/gn/bin/roll_gn.py", line 92, in Roll
    ret = self.WaitForBuildToFinish()
  File "tools/gn/bin/roll_gn.py", line 188, in WaitForBuildToFinish
    results = self.CheckBuild()
  File "tools/gn/bin/roll_gn.py", line 270, in CheckBuild
    fp = urllib2.urlopen(jsurl)
  File "/usr/lib/python2.7/urllib2.py", line 127, in urlopen
    return _opener.open(url, data, timeout)
  File "/usr/lib/python2.7/urllib2.py", line 410, in open
    response = meth(req, response)
  File "/usr/lib/python2.7/urllib2.py", line 523, in http_response
    'http', request, response, code, msg, hdrs)
  File "/usr/lib/python2.7/urllib2.py", line 442, in error
    result = self._call_chain(*args)
  File "/usr/lib/python2.7/urllib2.py", line 382, in _call_chain
    result = func(*args)
  File "/usr/lib/python2.7/urllib2.py", line 629, in http_error_302
    return self.parent.open(new, timeout=req.timeout)
  File "/usr/lib/python2.7/urllib2.py", line 410, in open
    response = meth(req, response)
  File "/usr/lib/python2.7/urllib2.py", line 523, in http_response
    'http', request, response, code, msg, hdrs)
  File "/usr/lib/python2.7/urllib2.py", line 448, in error
    return self._call_chain(*args)
  File "/usr/lib/python2.7/urllib2.py", line 382, in _call_chain
    result = func(*args)
  File "/usr/lib/python2.7/urllib2.py", line 531, in http_error_default
    raise HTTPError(req.get_full_url(), code, msg, hdrs, fp)
urllib2.HTTPError: HTTP Error 404: Not Found