Remove ignored bot_update "force" parameter.

scripts/slave/recipes/chromium_gn_upload.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',
   'file',
@@ skipping 48 matching lines @@
   },
 })
 
 
 def RunSteps(api):
   mastername = api.m.properties['mastername']
   buildername, bot_config = api.chromium.configure_bot(BUILDERS,
                                                        ['gn_for_uploads', 'mb'])
 
   api.bot_update.ensure_checkout(
-      force=True, patch_root=bot_config.get('root_override'))
+      patch_root=bot_config.get('root_override'))
 
   api.chromium.ensure_goma()
 
   api.chromium.runhooks()
 
   api.chromium.run_mb(mastername, buildername)
 
   api.chromium.compile(targets=['gn', 'gn_unittests'])
 
   path_to_binary = str(api.path['checkout'].join('out', 'Release', 'gn'))
@@ skipping 12 matching lines @@
              ['-b', 'chromium-gn', path_to_binary])
 
   sha1 = api.file.read('gn sha1', path_to_binary + '.sha1',
                        test_data='0123456789abcdeffedcba987654321012345678')
   api.step.active_result.presentation.step_text = sha1
 
 
 def GenTests(api):
   for test in api.chromium.gen_tests_for_builders(BUILDERS):
     yield test