Deadlock detection for Entity beans

Deadlock detection with EJB 2.1 entity beans and pessimistic locking does not work.
We are migrating our application from Jboss 4.05 where we used entity beans. This jboss version was able to detect deadlock situations and throw a org.jboss.util.deadlock.ApplicationDeadlockException. This mechanism does no longer work - instead of that both transactions just hang until a transaction timeout is reached.