filtered error log is constantly empty

[jdm]

No description provided.

[CYBAI]

For example, like this linux-rel-css build, it's failed at building time

Error running mach:

    ['filter-intermittents', 'wpt-errorsummary.log', '--log-intermittents', 'intermittents.log', '--log-filteredsummary', 'filtered-wpt-errorsummary.log', '--tracker-api', 'default', '--reporter-api', 'default']

The error occurred in code that was called by the mach command. This is either
a bug in the called code itself or in the way that mach is calling it.

You should consider filing a bug for this issue.

If filing a bug, please include the full output of mach, including this error
message.

The details of the failure are as follows:

HTTPError: HTTP Error 500: INTERNAL SERVER ERROR

  File "/home/servo/buildbot/slave/linux-rel-css/build/python/servo/testing_commands.py", line 551, in filter_intermittents
    response = urllib2.urlopen(request)
  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 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)

Should this kind of error only show failure of stdio?

[jdm]

Looks like our server isn't running.

[jdm]

Fixed in servo/saltfs#834.