Remove ignored bot_update "force" parameter.

scripts/slave/recipes/boringssl_docs.py

 # Copyright 2015 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.
 
 """Generates BoringSSL documentation and uploads it to Cloud Storage."""
 
 
 DEPS = [
   'chromium',
   'depot_tools/bot_update',
   'depot_tools/tryserver',
   'depot_tools/gclient',
   'gsutil',
   'recipe_engine/path',
   'recipe_engine/properties',
   'recipe_engine/python',
 ]
 
 
 def RunSteps(api):
   # Sync and pull in everything.
   api.gclient.set_config('boringssl')
-  api.bot_update.ensure_checkout(force=True)
+  api.bot_update.ensure_checkout()
   api.gclient.runhooks()
 
   # Set up paths.
   util = api.path['checkout'].join('util')
   go_env = util.join('bot', 'go', 'env.py')
   output = api.path.mkdtemp('boringssl-docs')
 
   # Generate and upload documentation.
   api.python('generate', go_env, ['go', 'run', 'doc.go', '-out', output],
              cwd=util)
@@ skipping 12 matching lines @@
   )
 
   yield (
     api.test('boringssl-docs-gerrit') +
     api.properties.tryserver_gerrit(
         gerrit_host='boringssl-review.googlesource.com',
         full_project_name='boringssl',
         mastername='actually-no-master', buildername='docs',
         slavename='swarming-slave')
   )