message: fix use after move
diff: @@ -225,7 +225,8 @@ bool parallel::emitOutput() {
  */
  stringstream new_ss;
  new_ss << line << '\n';
  - new_ss << move(parent_ss).str().substr(parent_ss.tellg());
  + auto cur = parent_ss.tellg();
  + new_ss << move(parent_ss).str().substr(cur);
  parent_ss.swap(new_ss);
  return false;
  }
  