Remove thirdparty/unittest2 from webkitpy and require python2.7.

Tools/Scripts/webkitpy/layout_tests/lint_test_expectations_unittest.py

 # Copyright (C) 2012 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
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+import StringIO
 import optparse
-import StringIO
-import webkitpy.thirdparty.unittest2 as unittest
+import unittest
 
 from webkitpy.common.host_mock import MockHost
 from webkitpy.layout_tests import lint_test_expectations
 
 
 class FakePort(object):
     def __init__(self, host, name, path):
         self.host = host
         self.name = name
         self.path = path
@@ skipping 149 matching lines @@
         lint_test_expectations.lint = interrupting_lint
         res = lint_test_expectations.main([], self.stdout, self.stderr)
         self.assertEqual(res, lint_test_expectations.INTERRUPTED_EXIT_STATUS)
 
     def test_exception(self):
         def exception_raising_lint(host, options):
             assert False
         lint_test_expectations.lint = exception_raising_lint
         res = lint_test_expectations.main([], self.stdout, self.stderr)
         self.assertEqual(res, lint_test_expectations.EXCEPTIONAL_EXIT_STATUS)