def change_index_dir(new_dir)
      logger.debug "[#{index_name}] changing index dir to #{new_dir}"
      index_definition[:index_dir] = index_definition[:ferret][:path] = new_dir
      reopen!
      logger.debug "[#{index_name}] index dir is now #{new_dir}"
    end
def change_index_dir(new_dir)
      logger.debug "[#{index_name}] changing index dir to #{new_dir}"
      index_definition[:index_dir] = index_definition[:ferret][:path] = new_dir
      reopen!
      logger.debug "[#{index_name}] index dir is now #{new_dir}"
    end
Switches the index to a new index directory.
 Used by the DRb server when switching to a new index version.