JCR_SQL2 queries don't see modifications inside a transaction the changes were made in

When Jackrabbit is used with JTA, Lucene index is updated on transaction commit. Due to this, changes made inside a transaction are not visible to queries run from inside the same transaction.

Steps to reproduce:
1. Begin JTA transaction.
2. Add a node.
3. Use a JCR_SQL2 query to find the node.
Expected: node is found.
Actual: node is not found.