QComboBox fusion style fails with stylesheet if no parent before setEditable

#include <QApplication>
#include <QWidget>
#include <QStyleFactory>
#include <QComboBox>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    a.setStyle(QStyleFactory::create("fusion"));
    a.setStyleSheet(" ");
    // use empty style sheet to see correct style
//    a.setStyleSheet("");
    QWidget* w = new QWidget();
    QComboBox* test = new QComboBox();
    // or set parent before setEditable to see correct style
//    test->setParent(w);
    test->setEditable(true);
    test->addItem("test1");
    test->addItem("test2");
    test->addItem("test3");
    test->setParent(w);
    w->show();
    a.exec();
}