Fix xtree patch check, and in turn C4702 disabling

build/win_is_xtree_patched.py

 #!/usr/bin/env python
 # 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.
 
 """Determines if the VS xtree header has been patched to disable C4702."""
 
 import os
 
 
 def IsPatched():
   # TODO(scottmg): For now, just return if we're using the packaged toolchain
   # script (because we know it's patched). Another case could be added here to
   # query the active VS installation and actually check the contents of xtree.
   # http://crbug.com/346399.
-  return os.environ.get('DEPOT_TOOLS_WIN_TOOLCHAIN', 1) == 0
+  return int(os.environ.get('DEPOT_TOOLS_WIN_TOOLCHAIN', 1)) == 1
 
 
 def DoMain(_):
   """Hook to be called from gyp without starting a separate python
   interpreter."""
-  return IsPatched()
+  return "1" if IsPatched() else "0"
 
 
 if __name__ == '__main__':
   print DoMain([])