docs: def disttar_suffix(env, sources):
          """tar archive suffix generator"""
  
          env_dict = env.Dictionary()
          if env_dict.has_key("DISTTAR_FORMAT") and env_dict["DISTTAR_FORMAT"] in ["gz", "bz2"]:
                  return ".tar." + env_dict["DISTTAR_FORMAT"]
          else:
                  return ".tar"