Declarative state machine asserts when triggering transition defined in top-level parallel states

import QtQuick 2.1
import QtQml.StateMachine 1.0

Item {
    id: root

    signal mySignal

    Component.onCompleted: {
        machine.start()
    }

    Timer {
        interval: 100
        running: true
        onTriggered: root.mySignal()
    }

    StateMachine {
        id: machine
        childMode: QState.ParallelStates
        State {
            id: parentState
            initialState: firstState
            SignalTransition { signal: root.mySignal; targetState: otherState }
            State { id: otherState; onEntered: console.log("entered otherstate");}
            State { id: firstState; onEntered: console.log("entered firststate"); }
        }
    }
}