FIX: default regex arg should be an empty string
FIX: default regex arg should be an empty string

rfaulkner/wikipedia_user_metrics,wikimedia/analytics-user-metrics,wikimedia/analytics-user-metrics,rfaulkner/wikipedia_user_metrics,wikimedia/user_metrics,wikimedia/analytics-user-metrics,wikimedia/user_metrics,rfaulkner/wikipedia_user_metrics,wikimedia/user_metrics