Remove unused imports and fix some other linter errors.

recipe_engine/unittests/run_test.py

 #!/usr/bin/env python
 # Copyright 2014 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 import json
 import os
 import re
 import subprocess
-import sys
 import unittest
 import tempfile
 import time
 
 import test_env
 from test_env import BASE_DIR
 
 import recipe_engine.run
 import recipe_engine.step_runner
 from recipe_engine import requests_ssl
-from recipe_engine import recipe_test_api
-import mock
 
 class RunTest(unittest.TestCase):
   def _run_cmd(self, recipe, properties=None, engine_args=None):
     script_path = os.path.join(BASE_DIR, 'recipes.py')
 
     if properties:
       proplist = [ '%s=%s' % (k, json.dumps(v))
                    for k,v in properties.iteritems() ]
     else:
       proplist = []
@@ skipping 164 matching lines @@
     self.assertRegexpMatches(stdout, r'(?m)^@@@BUILD_STEP@pippy@@@$')
     # Before 'Subannotate me' we expect an extra STEP_CURSOR to reset the
     # state.
     self.assertRegexpMatches(stdout,
         r'(?m)^@@@STEP_CURSOR@Subannotate me@@@\n@@@STEP_CLOSED@@@$')
 
 
 if __name__ == '__main__':
   unittest.TestCase.maxDiff = None
   unittest.main()