How to use onSqlOutput in formatted sql mode

Hi 

I'm using Liquibase in "formatted sql" mode (not XML syntax). I want each change set to have a precondition which is checked when generating the SQL using updateSQL. I tried the folowing syntax using "onSqlOutput:TEST", but it does not work:

--liquibase formatted sql

--changeset mike:32

--preconditions onSqlOutput:TEST onFail:HALT onError:HALT

--precondition-sql-check expectedResult: <here comes my SQL condition>

By the way, when using update (instead of updateSQL) it works as expected.

Thanks for any help,

Mike