How to drop db index from inherited itemType

Hi!

In H5.4 I'm trying to extend PriceRow and deploy it to new table:

 <itemtype code="PriceRowForOption" extends="PriceRow">

In PriceRow I have already defined one unique index. I want to drop this index in new type PriceRowForOption. But the attributes like:

 <index name="unique_listprice" unique="true" remove="true">

or

 <index name="unique_listprice" unique="true" replace="true">

does not work :(

The old index is created in new table without any change. Any idea why?