new_contents: #!/usr/bin/env python
  
  import os
  from os.path import expanduser
  home = expanduser("~")
  
  prefixes = os.environ.get('ENV_PREFIXES', 'TRAVIS CI encrypt TOKEN TESTS').split(' ')
  env_file = os.environ.get('ENV_FILE', os.path.join(home, 'env'))
  with open(env_file, 'wt') as env:
      for k,v in os.environ.items():
          for pref in prefixes:
              if k.startswith(pref):
                  env.write('{}="{}"\n'.format(k,v))
  
subject: add script to generate env file for docker on ci