paymod: Consider new payments when checking if an attempt is ongoing

Without this the flapping behavior tested in `test_pay_retry` would reappear.

plugins/pay.c

@@ -1507,7 +1507,11 @@ static struct command_result *json_paystatus(struct command *cmd,
 static bool attempt_ongoing(const char *b11)
 {
 	struct pay_status *ps;
+	struct payment *root;
 	struct pay_attempt *attempt;
+	struct payment_tree_result res;
+	enum payment_step diff,
+	    final_states = PAYMENT_STEP_FAILED | PAYMENT_STEP_SUCCESS;
 
 	list_for_each(&pay_status, ps, list) {
 		if (!streq(b11, ps->bolt11))
@@ -1515,6 +1519,14 @@ static bool attempt_ongoing(const char *b11)
 		attempt = &ps->attempts[tal_count(ps->attempts)-1];
 		return attempt->result == NULL && attempt->failure == NULL;
 	}
+
+	list_for_each(&payments, root, list) {
+		if (root->bolt11 == NULL || !streq(b11, root->bolt11))
+			continue;
+		res = payment_collect_result(root);
+		diff = res.leafstates & ~final_states;
+		return diff != 0;
+	}
 	return false;
 }