Make depot_tools' fetch work on windows if 'gclient' isn't in the 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 44 matching lines @@
 
   def sync(self):
     pass
 
 
 class GclientCheckout(Checkout):
 
   def run_gclient(self, *cmd, **kwargs):
     print 'Running: gclient %s' % ' '.join(pipes.quote(x) for x in cmd)
     if not self.dryrun:
-      return subprocess.check_call(('gclient',) + cmd, **kwargs)
+      return subprocess.check_call(
+          (sys.executable, os.path.join(SCRIPT_PATH, 'gclient.py')) + cmd,
+          **kwargs)
 
 
 class GitCheckout(Checkout):
 
   def run_git(self, *cmd, **kwargs):
     print 'Running: git %s' % ' '.join(pipes.quote(x) for x in cmd)
     if not self.dryrun:
       return subprocess.check_call(('git',) + cmd, **kwargs)
 
 
@@ skipping 152 matching lines @@
 
 
 def main():
   dryrun, recipe, props = handle_args(sys.argv)
   spec, root = run_recipe_fetch(recipe, props)
   return run(dryrun, spec, root)
 
 
 if __name__ == '__main__':
   sys.exit(main())