23466: Attach causal exception for DuplicateChildNodeNameException (ALF-5488, ALF-5540)
- Also add savepoints around these updates statements
- Propagate exception so that we can identify if something else (not duplicate child name) is at fault
git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@24837 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261