The test org.hibernate.test.hql.BulkManipulationTest#testInsertWithGeneratedTimestampVersion needs to be skipped for DB2. It is currently failing on line 78:

int count = s.createQuery( "insert into TimestampVersioned ( name ) select name from TimestampVersioned" ).executeUpdate();

because DB2 doesn't supports insert with select.

A solution is to check the org.hibernate.dialect.Dialect#supportsParametersInInsertSelect method before executing this piece of code.