Delete index.lock files before checking out master branch.

tools/auto_bisect/bisect_utils.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.
 
 """Utility functions used by the bisect tool.
 
 This includes functions related to checking out the depot and outputting
 annotations for the Buildbot waterfall.
 """
 
@@ skipping 292 matching lines @@
     path: The path name passed to func.
     _: Exception information from sys.exc_info(). Not used.
   """
   if not os.access(path, os.W_OK):
     os.chmod(path, stat.S_IWUSR)
     func(path)
   else:
     raise
 
 
-def _CleanupPreviousGitRuns():
+def _CleanupPreviousGitRuns(cwd=os.getcwd()):
   """Cleans up any leftover index.lock files after running git."""
   # If a previous run of git crashed, or bot was reset, etc., then we might
   # end up with leftover index.lock files.
-  for path, _, files in os.walk(os.getcwd()):
+  for path, _, files in os.walk(cwd):
     for cur_file in files:
       if cur_file.endswith('index.lock'):
         path_to_file = os.path.join(path, cur_file)
         os.remove(path_to_file)
 
 
 def RunGClientAndSync(cwd=None):
   """Runs gclient and does a normal sync.
 
   Args:
@@ skipping 87 matching lines @@
   Args:
     opts: The options parsed from the command line through parse_args().
     custom_deps: A dictionary of additional dependencies to add to .gclient.
   """
   if CheckIfBisectDepotExists(opts):
     path_to_dir = os.path.join(os.path.abspath(opts.working_directory),
                                BISECT_DIR, 'src')
     (output, _) = RunGit(['rev-parse', '--is-inside-work-tree'],
                          cwd=path_to_dir)
     if output.strip() == 'true':
+      # Before checking out master, cleanup up any leftover index.lock files.
+      _CleanupPreviousGitRuns(path_to_dir)
       # Checks out the master branch, throws an exception if git command fails.
       CheckRunGit(['checkout', '-f', 'master'], cwd=path_to_dir)
-
   if not _CreateAndChangeToSourceDirectory(opts.working_directory):
     raise RuntimeError('Could not create bisect directory.')
 
   if not SetupGitDepot(opts, custom_deps):
     raise RuntimeError('Failed to grab source.')
 
 
 def RunProcess(command):
   """Runs an arbitrary command.
 
@@ skipping 71 matching lines @@
     platform = os.environ.get('PROCESSOR_ARCHITECTURE')
   return platform and platform in ['AMD64', 'I64']
 
 
 def IsLinuxHost():
   return sys.platform.startswith('linux')
 
 
 def IsMacHost():
   return sys.platform.startswith('darwin')