Press event can not be accepted by MouseArea when it covers a Button

Steps to reproduce

1. Load QML code into QQuickView where MouseArea covers a Button

import QtQuick 2.0
import QtQuick.Controls 2.0

Item {
    width: 200; height: 200
    Button {
        anchors.fill: parent
    }
    MouseArea {
        id: ma
        anchors.fill: parent
        onPressed: mouse => mouse.accepted = true
    }
} 

2. Send a MouseButtonPress event into that QQuickView.

Actual result
MouseButtonPress event is NOT accepted.

Expected result
MouseButtonPress event is accepted.

Additional info

Removing a Button allows MouseArea to accept the event.
Attached a code snippet for qtdeclarative/tests/auto/quick/qquickmousearea/tst_qquickmousearea.cpp to illustrate the bug.