DERBY-6554: Raise SelfDeadlock when a nested subtransaction can't immediately get a lock because it is blocked by its parent transaction; commit derby-6554-02-ae-selfDeadlock_sps_compress.diff.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1593702 13f79535-47bb-0310-9956-ffa450edef68