old_contents: DEFAULT_SOURCE_DIR = 'hack-source'
  DEFAULT_BUILD_DIR = 'hack-build'
  DEFAULT_PACKAGE_DIR = 'hack-packages'
  
new_contents: #  Copyright 2012 Ooyala, Inc.
  #
  #  Licensed under the Apache License, Version 2.0 (the "License");
  #  you may not use this file except in compliance with the License.
  #  You may obtain a copy of the License at
  #
  #      http://www.apache.org/licenses/LICENSE-2.0
  #
  #  Unless required by applicable law or agreed to in writing, software
  #  distributed under the License is distributed on an "AS IS" BASIS,
  #  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  #  See the License for the specific language governing permissions and
  #  limitations under the License.
  
  DEFAULT_SOURCE_DIR = 'hack-source'
  DEFAULT_BUILD_DIR = 'hack-build'
  DEFAULT_PACKAGE_DIR = 'hack-packages'
  
subject: Add copyright notice to common.py.