Adding a non-nullable column to existing table fails. Is the “value” attribute being ignored?

Question

Background: we have a Grails 1.3.7 app and are using Liquibase to manage our database migrations.

I am trying to add a new column to an existing table which is not empty.

My changeset looks like this:

    changeSet(author: "someCoolGuy (generated)", id: "1326842592275-1") {
        addColumn(tableName: "layer") {
            column(name: "abstract_trimmed", type: "VARCHAR(455)", value: "No text") {
                constraints(nullable: "false")
            }
        }
    }

Which should have inserted the value 'No text' into every existing row, and therefore satisfied the not null constraint. Liquibase "Add Column" docs.

But when the migrations changesets are being applied I get the following exception:

liquibase.exception.DatabaseException: Error executing SQL ALTER TABLE layer ADD abstract_trimmed VARCHAR(455) NOT NULL: ERROR: column "abstract_trimmed" contains null values

Which looks to me like it is not using the 'value' attribute.

If I change my changeset to work look like the following I can achieve the same thing. But I don't want to (and shouldn't have to) do this.

    changeSet(author: "someCoolGuy (generated)", id: "1326842592275-1") {
        addColumn(tableName: "layer") {
            column(name: "abstract_trimmed", type: "VARCHAR(455)")
        }

        addNotNullConstraint(tableName: "layer", columnName:"abstract_trimmed", defaultNullValue: "No text")
    }

Is Liquibase really ignoring my value attribute, or is there something else going on here that I can't see?

I am using Grails 1.3.7, Database-migration plugin 1.0, Postgres 9.0