old_contents: var PROPERTY_SS_ID = 'SPREADSHEET_ID';
  var RULE_KEY = 'MAILMAN_PROP_RULES';
  var MAILMAN_VERSION = 'pre0.11';
  
  var SPREADSHEET_ID = null;
  
new_contents: var PROPERTY_SS_ID = 'SPREADSHEET_ID';
  var RULE_KEY = 'MAILMAN_PROP_RULES';
  var MAILMAN_VERSION = 'pre0.12';
  
  var SPREADSHEET_ID = null;
  
subject: Increment the version number.