new_contents: # Licensed to Elasticsearch under one or more contributor
  # license agreements. See the NOTICE file distributed with
  # this work for additional information regarding copyright
  # ownership. Elasticsearch licenses this file to you 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.
  
  '''
  Downloads and extracts elasticsearch for backwards compatibility tests.
  '''
  
  import argparse
  import os
  import platform
  import shutil
  import subprocess
  import urllib.request
  import zipfile
  
  def parse_config():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument('--path', metavar='DIR', default='./backwards',
                        help='Where to extract elasticsearch')
    parser.add_argument('--force', action='store_true', default=False,
                        help='Delete and redownload if the version already exists')
    parser.add_argument('version', metavar='X.Y.Z',
                        help='Version of elasticsearch to grab')
    return parser.parse_args()
  
  def main():
    c = parse_config()
    
    if not os.path.exists(c.path):
      print('Creating %s' % c.path)
      os.mkdir(c.path)
  
    is_windows = platform.system() == 'Windows'
  
    os.chdir(c.path)
    version_dir = 'elasticsearch-%s' % c.version
    if os.path.exists(version_dir):
      if c.force:
        print('Removing old download %s' % version_dir)
        shutil.rmtree(version_dir)
      else:
        print('Version %s exists at %s' % (c.version, version_dir))
        return 
  
    # before 1.4.0, the zip file contains windows scripts, and tar.gz contained *nix scripts
    if is_windows:
      filename = '%s.zip' % version_dir
    else:
      filename = '%s.tar.gz' % version_dir
  
    url = 'https://download.elasticsearch.org/elasticsearch/elasticsearch/%s' % filename
    print('Downloading %s' % url)
    urllib.request.urlretrieve(url, filename)
  
    print('Extracting to %s' % version_dir)
    if is_windows:
      archive = zipfile.ZipFile(filename)
      archive.extractall() 
    else:
      # for some reason python's tarfile module has trouble with ES tgz?
      subprocess.check_call('tar -xzf %s' % filename, shell=True)
  
    print('Cleaning up %s' % filename)
    os.remove(filename)
  
  if __name__ == '__main__':
    try:
      main()
    except KeyboardInterrupt:
      print('Ctrl-C caught, exiting')
  
subject: Add script to grab ES version for BWC tests.