Remove ignored bot_update "force" parameter.

scripts/slave/recipes/dart/dart_cross_compiler.py

 # Copyright 2016 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',
   'depot_tools/gclient',
   'file',
   'gsutil',
   'recipe_engine/path',
@@ skipping 22 matching lines @@
     'target_arch': 'x64',
     'clobber': True},
 }
 
 def tarball_name(arch, mode, revision):
   return 'cross_build_%s_%s_%s.tar.bz2' % (arch, mode, revision)
 
 def RunSteps(api):
   api.gclient.set_config('dart')
   api.path.c.dynamic_paths['tools'] = None
-  update_step = api.bot_update.ensure_checkout(force=True)
+  update_step = api.bot_update.ensure_checkout()
   revision = update_step.json.output['fixed_revisions']['sdk']
 
   api.path['tools'] = api.path['checkout'].join('tools')
   buildername = str(api.properties.get('buildername')) # Convert from unicode.
   (buildername, _, channel) = buildername.rpartition('-')
   assert channel in ['be', 'dev', 'stable', 'integration']
   buildername = buildername.replace('-recipe', '')
   b = builders[buildername]
 
   if b.get('clobber', False):
@@ skipping 34 matching lines @@
     api.platform('linux', 64) +
     api.properties.generic(mastername='client.dart',
                            buildername='cross-arm-vm-linux-release-recipe-be',
                            revision='abcd1234efef5656'))
   yield (
     api.test('clobber-coverage') +
     api.platform('linux', 64) +
     api.properties.generic(mastername='client.dart',
                            buildername='test-coverage-stable',
                            revision='abcd1234efef5656'))