Strange difference between implicit and explicit joins with left correlation

Using the Don C tutorial data, the following "equivalent" queries return different results:

SELECT * FROM customers c, (select value o from orders o where o.custid = c.custid) o
WHERE c.custid = o.custid
LIMIT 1;

(returns the inner join of customers and orders as expected)

SELECT * FROM customers c JOIN (select value o from orders o where o.custid = c.custid) o
ON c.custid = o.custid
LIMIT 1;

(returns an empty result)