repl.start({
  prompt: 'remote> ',
  input: sock,
  output: sock,  // (replace this with process.stdout and autocomplete works fine)
  terminal: true
});

Problem: Tab-autocomplete will only display empty lines. (Tested on 0.10.32 win, 0.10.29 linux).
Workaround: Set sock.columns=80;

Probable cause:
https://github.com/joyent/node/blob/master/lib/readline.js#L414
results in minRows = 0, because maxColumns=Infinity (via #L382, from #L158)