Remove ignored bot_update "force" parameter.

scripts/slave/recipes/chromium_libfuzzer.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 86 matching lines @@
           ] + args,
           stdout=api.raw_io.output())
   return step_result.stdout.split()
 
 
 def RunSteps(api):
   mastername = api.m.properties['mastername']
   buildername, bot_config = api.chromium.configure_bot(BUILDERS, ['mb'])
 
   checkout_results = 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)
 
   all_fuzzers = gn_refs(
           api,
           'calculate all_fuzzers',
           ['--all',
            '--type=executable',
            '--as=output',
@@ skipping 50 matching lines @@
 
 def GenTests(api):
   for test in api.chromium.gen_tests_for_builders(BUILDERS):
     yield (test +
            api.step_data('calculate all_fuzzers',
                stdout=api.raw_io.output('target1 target2 target3')) +
            api.step_data('calculate no_clusterfuzz',
                stdout=api.raw_io.output('target1'))
            )