Remove ignored bot_update "force" parameter.

scripts/slave/recipes/v8/infra_end_to_end.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.
 
 import re
 
 DEPS = [
   'depot_tools/bot_update',
   'depot_tools/gclient',
   'recipe_engine/json',
@@ skipping 50 matching lines @@
         'name': 'verify suspects',
         'regexp': r'Suspecting multiple commits(?:.|\s)*'
                   r'd290f204(?:.|\s)*c08e9525',
       },
     ],
   },
 ]
 
 def RunSteps(api):
   api.gclient.set_config('build')
-  api.bot_update.ensure_checkout(force=True)
+  api.bot_update.ensure_checkout()
 
   for test in TESTS:
     try:
       api.python(
           name=test['name'],
           script=api.path['checkout'].join(
               'scripts', 'tools', 'run_recipe.py'),
           args=[
             'v8',
             '--properties-file',
@@ skipping 46 matching lines @@
       ) +
       api.override_step_data(
           'Test auto-bisect on tester',
           api.raw_io.stream_output(
               'Suspecting multiple commits\ndeadbeef\ndeadbeef',
               stream='stdout',
           ),
           retcode=1,
       )
   )