"strange" behaviour when using QRadioButtons

The following example demonstrates strange behavior with autoExclusivity.

#include <QApplication>
#include <QWidget>
#include <QVBoxLayout>
#include <QFrame>
#include <QRadioButton>

int main(int argc, char **argv)
{
QApplication a(argc, argv);
QWidget w;
QVBoxLayout *l = new QVBoxLayout(&w);
QFrame *frame = new QFrame(&w);
frame->setFrameStyle(QFrame::Raised);
l->addWidget(frame);
QVBoxLayout *frameLayout = new QVBoxLayout(frame);
frameLayout->addWidget(new QRadioButton("&1", frame));
frameLayout->addWidget(new QRadioButton("&2", frame));
l->addWidget(new QRadioButton("&3", &w));
l->addWidget(new QRadioButton("&4", &w));
w.show();
return a.exec();
}

To reproduce:

first issue:
run app
click 3
click 4 (notice that 3 gets unchecked)
click 1 (notice that 4 remains checked. This is expected)
click 2 (notice that 4 remains checked and 1 gets unchecked. This is expected)
click 3 (notice that 4 remains checked. This is not expected)

second issue:
comment out button 2

run app
click 1
click 2 (notice that 1 gets unchecked. This is a little unexpected)
click 3 (notice that 2 gets unchecked. This is expected)
click 2 (notice that 3 gets unchecked. This is expected)
click 1 (notice 2 remains checked. This is unexpected)