Don't hardcode git directory path.

fetch.py

 #!/usr/bin/env python
 # Copyright (c) 2013 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.
 
 """
 Tool to perform checkouts in one easy command line!
 
 Usage:
   fetch <recipe> [--property=value [--property2=value2 ...]]
@@ skipping 61 matching lines @@
       cmd_prefix = (sys.executable, os.path.join(SCRIPT_PATH, 'gclient.py'))
     else:
       cmd_prefix = ('gclient',)
     return self.run(cmd_prefix + cmd, **kwargs)
 
 
 class GitCheckout(Checkout):
 
   def run_git(self, *cmd, **kwargs):
     if sys.platform == 'win32' and not spawn.find_executable('git'):
-      git_path = os.path.join(SCRIPT_PATH, 'git-1.8.0_bin', 'bin', 'git.exe')
+      git_path = os.path.join(SCRIPT_PATH, 'git.bat')
     else:
       git_path = 'git'
     return self.run((git_path,) + cmd, **kwargs)
 
 
 class SvnCheckout(Checkout):
 
   def run_svn(self, *cmd, **kwargs):
     if sys.platform == 'win32' and not spawn.find_executable('svn'):
       svn_path = os.path.join(SCRIPT_PATH, 'svn_bin', 'svn.exe')
@@ skipping 197 matching lines @@
 
 
 def main():
   options, recipe, props = handle_args(sys.argv)
   spec, root = run_recipe_fetch(recipe, props)
   return run(options, spec, root)
 
 
 if __name__ == '__main__':
   sys.exit(main())