Add connection breakage.

infra/libs/buildbot/test/master_test.py

 # Copyright 2015 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.
 
 import collections
 import json
 import os
 import requests
 import simplejson
 import subprocess
@@ skipping 129 matching lines @@
     self.res = self.Response(
         status_code=200,
         json=raiser)
     self.mock(requests, 'get', self.requests_handler)
     self.assertFalse(master.get_accepting_builds(self.chromium_fyi))
 
   def testTimeout(self):
     def timeout(*_args, **_kwargs):
       raise requests.exceptions.Timeout('timeout')
     self.mock(requests, 'get', timeout)
-    self.assertFalse(master.get_accepting_builds(self.chromium_fyi))
+    self.assertIsNone(master.get_accepting_builds(self.chromium_fyi))
+
+  def testConnectionErr(self):
+    def timeout(*_args, **_kwargs):
+      raise requests.exceptions.ConnectionError('error')
+    self.mock(requests, 'get', timeout)
+    self.assertIsNone(master.get_accepting_builds(self.chromium_fyi))
 
 class TestMasterManipulation(auto_stub.TestCase):
   def setUp(self):
     super(TestMasterManipulation, self).setUp()
     self.chromium_fyi = os.path.join(DATA_DIR, 'master.chromium.fyi')
 
   def testWithGclientSyncEnabled(self):
     actions = list(master.convert_action_items_to_cli((
       master.GclientSync,
       master.MakeStop,
@@ skipping 22 matching lines @@
     self.assertEquals(
         [a['cmd'] for a in actions],
         [
           ['make', 'stop'],
         ],
     )
 
   def testInvalid(self):
     with self.assertRaises(ValueError):
       list(master.convert_action_items_to_cli((-100,), self.chromium_fyi))