tried to use puppetlabs-bash_task_helper, and task-succeed seems working fine, but task-fail chokes

The task failed with exit code 1
  {
    "status": "error",
    "_output": "iconv: unrecognized option '--unicode-subst=\u%04x'\nTry `iconv --help' or `iconv --usage' for more information.\ndeployment failed"
  }