Revert of Remove unused imports in webkitpy.

third_party/WebKit/Tools/Scripts/webkitpy/common/net/buildbot/buildbot.py

 # Copyright (c) 2009, Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
 # in the documentation and/or other materials provided with the
 # distribution.
 #     * Neither the name of Google Inc. nor the names of its
 # contributors may be used to endorse or promote products derived from
 # this software without specific prior written permission.
 #
 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 import json
+import operator
 import re
 import urllib
 import urllib2
 
 import webkitpy.common.config.urls as config_urls
 from webkitpy.common.memoized import memoized
 from webkitpy.common.net.layouttestresults import LayoutTestResults
 from webkitpy.common.net.networktransaction import NetworkTransaction
 from webkitpy.common.system.logutils import get_logger
 from webkitpy.thirdparty.BeautifulSoup import BeautifulSoup
@@ skipping 350 matching lines @@
 
             builders_succeeded_in_past = set()
             for past_revision in revisions_in_order[i:]:
                 if not revision_statuses[past_revision]:
                     break
                 builders_succeeded_in_past = builders_succeeded_in_past.union(revision_statuses[past_revision])
 
             if len(builders_succeeded_in_future) == len(builder_revisions) and len(builders_succeeded_in_past) == len(builder_revisions):
                 return revision
         return None