Mocks are not used by the delegate of a closure

import groovy.mock.interceptor.StubFor

class Foo {
    def createBar() {
        throw new RuntimeException("We should never get here!")
    }
}

StubFor fooStub = new StubFor(Foo)

fooStub.demand.createBar { "I'm a mock" }

Closure closure = { createBar() }

fooStub.use {
    Foo foo = new Foo()
    assert "I'm a mock" == foo.createBar()
    closure.delegate = foo
    assert "I'm a mock" == closure.call()
}