This build:

https://uberchromegw.corp.google.com/i/chromeos/builders/master-paladin/builds/14046

Ran this suite:

http://cautotest/tko/retrieve_logs.cgi?job=/results/108313640-chromeos-test/

Which died with repeated 500 errors like this from the devserver:




        500 Internal Server Error
          The server encountered an unexpected condition which prevented it from fulfilling the request.
          Traceback (most recent call last):
    File "/usr/lib64/python2.7/site-packages/cherrypy/_cprequest.py", line 656, in respond
      response.body = self.handler()
    File "/usr/lib64/python2.7/site-packages/cherrypy/lib/encoding.py", line 188, in __call__
      self.body = self.oldhandler(*args, **kwargs)
    File "/usr/lib64/python2.7/site-packages/cherrypy/_cpdispatch.py", line 34, in __call__
      return self.callable(*self.args, **self.kwargs)
    File "/usr/lib/devserver/devserver.py", line 788, in is_staged
      response = str(dl.IsStaged(factory))
    File "/usr/lib/devserver/downloader.py", line 216, in IsStaged
      raise DownloaderException(exceptions)
  DownloaderException: [Errno 2] No such file or directory: u'/mnt/moblab/static/cyan-release/R55-8872.67.0/.test_suitesDOTtarDOTbz2'
  Traceback (most recent call last):
    File "/usr/lib/devserver/build_artifact.py", line 343, in Process
      self._MarkArtifactStaged()
    File "/usr/lib/devserver/build_artifact.py", line 238, in _MarkArtifactStaged
      with open(os.path.join(self.install_dir, self.marker_name), 'w') as f:
  IOError: [Errno 2] No such file or directory: u'/mnt/moblab/static/cyan-release/R55-8872.67.0/.test_suitesDOTtarDOTbz2'
  
  
      
      Powered by CherryPy 3.2.2
      
      
  
  
  Traceback (most recent call last):
    File "/usr/local/autotest/frontend/afe/json_rpc/serviceHandler.py", line 120, in dispatchRequest
      results['result'] = self.invokeServiceEndpoint(meth, args)
    File "/usr/local/autotest/frontend/afe/json_rpc/serviceHandler.py", line 160, in invokeServiceEndpoint
      return meth(*args)
    File "/usr/local/autotest/frontend/afe/rpc_handler.py", line 270, in new_fn
      return f(*args, **keyword_args)
    File "/usr/local/autotest/frontend/afe/rpc_utils.py", line 1159, in replacement
      return func(**kwargs)
    File "/usr/local/autotest/frontend/afe/rpc_interface.py", line 1788, in create_suite_job
      test_source_build, hostname=sample_dut)
    File "/usr/local/autotest/frontend/afe/rpc_interface.py", line 1668, in _stage_build_artifacts
      "Failed to stage %s on %s: %s" % (build, ds_name, e))
  StageControlFileFailure: Failed to stage cyan-release/R55-8872.67.0 on 192.168.231.1: 
  
  
      
      500 Internal Server Error
      
      #powered_by {
          margin-top: 20px;
          border-top: 2px solid black;
          font-style: italic;
      }
  
      #traceback {
          color: red;
      }