Unable to define a custom test phase with Grails 2.0

I use the technique described here (http://ldaley.com/post/615966534/custom-grails-test) to define a custom functional test phase.

Here is how I do it:

import grails.plugin.spock.test.GrailsSpecTestType

eventAllTestsStart = {
    def testTypeName = "custom"
    def testDirectory = "custom"
    customTests = [new GrailsSpecTestType(testTypeName, testDirectory)]

    phasesToRun << "custom"
}

With 1.3.7, it works fine, but with 2.0.0, the compilation fails saying that it cannot resolve the class 'grails.plugin.spock.test.GrailsSpecTestType'

It was discussed on the Grails/Geb mailing list here (http://markmail.org/message/z453wagmpvjxluih), where Luke Daley confirmed that there was some regression in this area.