Failed renewal orders ought to update the order status to failed.

[peterwilsoncc]

The process_subscription_payment() method throws an exception when a payment fails, instead it should call $order->update_status( 'failed' ); to allow subscriptions to action the failure correctly.

Subscriptions hooks in to the woocommerce_order_status_changed action to record whether a payment is successful or fails. This hook is used to trigger various flows, including the retrying of payments.

PR incoming.