The main purpose is to apply and handler after all pending requests are
satisfied and allow process answer packets of current state out of order.
This fix a bug that appears when a storage tries to get a lock on an object that
is already held by a previous transaction. Is this case the store is delayed
causing the answer packet be sent out of order (packet sequence breakage), so
unexpected from client's point of view.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@1874 71dcc9de-d417-0410-9af5-da40c76e7ee4