man teamd.conf:
  runner.agg_select_policy (string)
  (...)
    port_options — Aggregator with highest priority according to per-port

Actual code:
  static const char *lacp_agg_select_policy_names_list[] = {
    "lacp_prio", "lacp_prio_stable", "bandwidth", "count", "port_config",
  };

I'd send a patch, but I have no idea which one to fix. Jiri?