Remove ignored bot_update "force" parameter.

scripts/slave/recipes/v8/auto_roll_v8rel.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.
 
 DEPS = [
   'depot_tools/bot_update',
   'chromium',
   'depot_tools/gclient',
   'depot_tools/git',
   'gsutil',
   'recipe_engine/json',
   'recipe_engine/path',
   'recipe_engine/properties',
   'recipe_engine/step',
   'v8',
 ]
 
 def RunSteps(api):
   api.chromium.cleanup_temp()
   api.gclient.set_config('chromium')
   api.gclient.apply_config('v8')
   api.bot_update.ensure_checkout(
-      force=True, no_shallow=True, with_branch_heads=True)
+      no_shallow=True, with_branch_heads=True)
   api.step(
       'V8Releases',
       [api.path['slave_build'].join(
            'v8', 'tools', 'release', 'releases.py'),
        '-c', api.path['checkout'],
        '--json', api.path['slave_build'].join('v8-releases-update.json'),
        '--branch', 'recent',
        '--work-dir', api.path['slave_build'].join('workdir')],
       cwd=api.path['slave_build'].join('v8'),
     )
   api.gsutil.upload(api.path['slave_build'].join('v8-releases-update.json'),
                     'chromium-v8-auto-roll',
                     api.path.join('v8rel', 'v8-releases-update.json'))
 
 
 def GenTests(api):
   yield api.test('standard') + api.properties.generic(
       mastername='client.v8.fyi')