Fix try job status PRESUBMIT check when an issue is private....

PRESUBMIT.py

 #!/usr/bin/python
 # Copyright (c) 2009 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Top-level presubmit script for Chromium.
 
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for details on the presubmit API built into gcl.
 """
@@ skipping 68 matching lines @@
   if not input_api.change.issue or not input_api.change.patchset:
     return outputs
   url = "http://codereview.chromium.org/%d/get_build_results/%d" % (
             input_api.change.issue, input_api.change.patchset)
   PLATFORMS = ('win', 'linux', 'mac')
   try:
     connection = input_api.urllib2.urlopen(url)
     # platform|status|url
     values = [item.split('|', 2) for item in connection.read().splitlines()]
     connection.close()
+    if not values:
+      # It returned an empty list. Probably a private review.
+      return outputs
     # Reformat as an dict of platform: [status, url]
     values = dict([[v[0], [v[1], v[2]]] for v in values])
     for platform in PLATFORMS:
       values.setdefault(platform, ['not started', ''])
     message = None
     non_success = [k.upper() for k,v in values.iteritems() if v[0] != 'success']
     if 'failure' in [v[0] for v in values.itervalues()]:
       message = 'Try job failures on %s!\n' % ', '.join(non_success)
     elif non_success:
       message = ('Unfinished (or not even started) try jobs on '
@@ skipping 34 matching lines @@
         connection = input_api.urllib2.urlopen(url_text)
         long_text = connection.read().strip()
         connection.close()
       except IOError:
         pass
       return [output_api.PresubmitError("The tree is closed.",
                                         long_text=long_text)]
   except IOError:
     pass
   return []