Upgrade from 4.2 to 4.3.x fails when using Oracle

From CONF-15228

Upgrading from 4.2 to 4.3.1 and I got the same bloody error with Oracle 10g and it is about time to fix it ,or at least mention it in the upgrade notes please, because I have spent quite amount of time searching for the solution:
2012-10-05 15:39:12,624 ERROR [main] [hibernate.tool.hbm2ddl.SchemaUpdate] execute Unsuccessful: create index attch_data_idx on ATTACHMENTDATA (ATTACHMENTID)

2012-10-05 15:39:12,632 ERROR [main] [hibernate.tool.hbm2ddl.SchemaUpdate] execute ORA-01408: such column list already indexed
the upgrade was performed when I added the famous line to the confluence.cfg.xml file:
<property name="hibernate.hbm2ddl.skip_creating_missing_indexes">true</property>
don't know if that will have some sort of side effects...
I would also like to mention that we did not perform any customization in the indexes. The indexes were created by the fresh installation of Confluence version 4.2
Angel Ruiz added a comment - 05/Oct/12 4:39 PM
Maybe the problem comes from the fact that it is still using Hibernate 2.1.X. Holy s**t!!!
I cannot even use the Oracle10G dialect in the confluence.cfg.xml file.