f clarify test comment

lightning/src/ln/offers_tests.rs

@@ -2319,8 +2319,10 @@ fn no_double_pay_with_stale_channelmanager() {
 
  // Alice receives a duplicate invoice, but the payment should be transitioned to Retryable by now.
  nodes[0].onion_messenger.handle_onion_message(bob_id, &invoice_om);
- // Previously we would've attempted to pay the invoice a 2nd time, resulting in a PaymentFailed
- // event here.
+ // Previously, Alice would've attempted to pay the invoice a 2nd time. In this test case, this 2nd
+ // attempt would have resulted in a PaymentFailed event here, since the only channnel between
+ // Alice and Bob is closed. Since no 2nd attempt should be made, check that no events are
+ // generated in response to the duplicate invoice.
  assert!(nodes[0].node.get_and_clear_pending_events().is_empty());
 }