danni | wjt: [danni@mendiculus ~]$ ~/src/install/bin/bustle call.bustle 
 danni | bustle: "UnmarshalError \"Invalid signature: \\\"h\\\"\""
 danni | :(

There are really two issues here. The first is that bustle-pcap, which uses GDBus, understands file handles (and hence puts messages containing them into the logs); whereas Bustle itself, which uses dbus-core, does not.

The second is:

  readPcap :: FilePath -> IO (Either IOError [B.DetailedMessage])
  readPcap path = try $ do
      p <- openOffline path
  
      ret <- evalStateT (mapBodies p convert) Map.empty
      -- FIXME: make the error handling less shoddy
      case ret of
          Left e -> error $ show e
          Right xs -> return xs

so Bustle just crashes rather than showing any kind of meaningful diagnostic and recovering.