wsp threads wait

usage: wsp threads wait <thread>... [--timeout <s>] [--tail]
  blocks until one of the threads leaves running and prints its finished line,
  with the reply whole under it; --tail prints the reply's last line alone,
  which is what a notify sends, and --timeout gives up after so many seconds and
  says so on stderr

  --timeout    how long to wait before answering that they are still running
  --tail       print the reply's last line alone, the line a notify sends,
               rather than the whole reply
  --json       print the raw protocol values, one JSON object per line, with
               everything else on stderr
  --state      the state file the host serves
  --host       run the line against a host on your account, by the name wsp
               hosts lists it under; WSP_HOST names one for a whole shell