Remove ignored bot_update "force" parameter.

scripts/slave/recipes/closure_compilation.py

 # Copyright 2014 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.
 
 from recipe_engine.types import freeze
 
 DEPS = [
   'depot_tools/bot_update',
   'chromium',
   'depot_tools/gclient',
@@ skipping 13 matching lines @@
     'buildername': 'closure_compilation',
     'testname': 'closure_compilation_try',
   },
 })
 
 
 def RunSteps(api):
   api.gclient.set_config('chromium')
   api.chromium.set_config('ninja')
 
-  api.bot_update.ensure_checkout(force=True)
+  api.bot_update.ensure_checkout()
 
   api.python(
       'run_tests',
       api.path['checkout'].join('third_party', 'closure_compiler',
                                 'run_tests.py')
   )
 
   api.step(
       'generate_gyp_files',
       [api.path['checkout'].join('build', 'gyp_chromium'),
@@ skipping 15 matching lines @@
 
 def GenTests(api):
   for mastername, config in MASTERS.iteritems():
     yield (
       api.test(config['testname']) +
       api.properties.generic(
           buildername=config['buildername'],
           mastername=mastername,
       )
     )