Repeated unlocking causes errors with reference counting

Taken from ISPN-2458:

When the lock is acquired after the first unlock, the second unlock fails with an IllegalMonitorStateException in OwnableReentrantLock.tryAcquire(...), but the reference count is still decremented in AbstractPerEntryLockContainer.releaseLock(...). This results in further IllegalStateException: Negative reference count for lock.

If the ISE occurs, the lock counter should not be affected.