Remove ignored bot_update "force" parameter.

scripts/slave/recipes/chromium_libfuzzer_clang_tot.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.
 
 import re
 from recipe_engine.types import freeze
 
 DEPS = [
   'archive',
   'depot_tools/bot_update',
@@ skipping 24 matching lines @@
     },
   },
 })
 
 
 def RunSteps(api):
   mastername = api.m.properties['mastername']
   buildername, bot_config = api.chromium.configure_bot(BUILDERS, ['mb'])
 
   api.bot_update.ensure_checkout(
-      force=True, patch_root=bot_config.get('root_override'))
+      patch_root=bot_config.get('root_override'))
 
   api.chromium.runhooks()
   api.chromium.run_mb(mastername, buildername, use_goma=False)
 
   api.chromium.compile(targets=['empty_fuzzer'])
 
   config_kwargs = bot_config.get('chromium_config_kwargs', dict())
   build_config = config_kwargs.get('BUILD_CONFIG', 'Release')
   build_dir=api.path['slave_build'].join('src', 'out', build_config)
 
   api.step('running empty_fuzzer', [api.path.join(build_dir, 'empty_fuzzer'),
                                     '-runs=1'])
 
 
 def GenTests(api):
   for test in api.chromium.gen_tests_for_builders(BUILDERS):
     yield test