Remove ignored bot_update "force" parameter.

scripts/slave/recipe_modules/pgo/api.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 import recipe_api
 
 
 # List of the benchmark that we run during the profiling step.
 #
 # TODO(sebmarchand): Move this into a BenchmarkSuite in telemetry, this way
@@ skipping 93 matching lines @@
     it and then compiling the optimized version of it.
     """
     self.m.gclient.set_config(bot_config['gclient_config'])
 
     # Augment the solution if needed.
     self.m.gclient.c.solutions[0].url += bot_config.get('url_suffix', '')
 
     if self.m.properties.get('slavename') != 'fake_slave':
       self.m.chromium.taskkill()
 
-    self.m.bot_update.ensure_checkout(force=True)
+    self.m.bot_update.ensure_checkout()
     if bot_config.get('patch_root'):
       self.m.path['checkout'] = self.m.path['slave_build'].join(
           bot_config.get('patch_root'))
 
     # First step: compilation of the instrumented build.
     self._compile_instrumented_image(bot_config)
 
     # Second step: profiling of the instrumented build.
     self._run_pgo_benchmarks()
 
     # Third step: Compilation of the optimized build, this will use the
     #     profile data files produced by the previous step.
     self._compile_optimized_image(bot_config)