Using attached Drag property crashes on iOS

import QtQuick 2.4
import QtQuick.Window 2.2

Window {
    visible: true

    Rectangle {
        id: draggable
        color: "red"
        width: 100; height: 50
        Drag.dragType: Drag.Automatic
        Drag.active: dragArea.drag.active
        Text {
            anchors.centerIn: parent
            text: "drag me"
        }
    }

    MouseArea {
        id: dragArea
        drag.target: draggable
        anchors.fill: draggable
    }

    Rectangle {
        color: dropArea.containsDrag ? "green" : "blue"
        x: 100; y: 100; width: 100; height: 50
        DropArea {
            id: dropArea
            anchors.fill: parent
        }
        Text {
            anchors.centerIn: parent;
            text: "here"
        }
    }
}

#0	0x00000001005d3d44 in QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData> >::data() const at /work/build/qt5_workdir/w/s/qtbase/src/gui/../../include/QtCore/../../src/corelib/tools/qscopedpointer.h:135
#1	0x000000010061ce10 in QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData> >::pointer qGetPtrHelper<QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData> > >(QScopedPointer<QObjectData, QScopedPointerDeleter<QObjectData> > const&) at /work/build/qt5_workdir/w/s/qtbase/src/gui/../../include/QtCore/../../src/corelib/global/qglobal.h:961
#2	0x000000010061d074 in QOpenGLContext::d_func() at /work/build/qt5_workdir/w/s/qtbase/src/gui/../../include/QtGui/../../src/gui/kernel/qopenglcontext.h:141
#3	0x00000001008c19c0 in QOpenGL2PaintEngineEx::begin(QPaintDevice*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/opengl/qopenglpaintengine.cpp:2074
#4	0x000000010082f1c0 in QPainter::begin(QPaintDevice*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/painting/qpainter.cpp:1808
#5	0x000000010082e8f8 in QPainter::QPainter(QPaintDevice*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/painting/qpainter.cpp:1471
#6	0x000000010082b700 in QPainter::QPainter(QPaintDevice*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/painting/qpainter.cpp:1474
#7	0x00000001005bc308 in QShapedPixmapWindow::render() at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qshapedpixmapdndwindow.cpp:70
#8	0x00000001005bc56c in QShapedPixmapWindow::exposeEvent(QExposeEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qshapedpixmapdndwindow.cpp:103
#9	0x00000001005dad64 in QWindow::event(QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qwindow.cpp:2025
#10	0x0000000100fee8f8 in QCoreApplicationPrivate::notify_helper(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qcoreapplication.cpp:1052
#11	0x0000000100fee85c in QCoreApplication::notify(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qcoreapplication.cpp:997
#12	0x00000001005c2dfc in QGuiApplication::notify(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qguiapplication.cpp:1528
#13	0x0000000100fee6f4 in QCoreApplication::notifyInternal(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qcoreapplication.cpp:935
#14	0x00000001005cc568 in QCoreApplication::sendSpontaneousEvent(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:231
#15	0x00000001005c6efc in QGuiApplicationPrivate::processExposeEvent(QWindowSystemInterfacePrivate::ExposeEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qguiapplication.cpp:2610
#16	0x00000001005c31fc in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qguiapplication.cpp:1635
#17	0x00000001005b219c in QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qwindowsysteminterface.cpp:572
#18	0x00000001005b17b8 in QWindowSystemInterface::flushWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qwindowsysteminterface.cpp:556
#19	0x00000001000c3f24 in -[QUIView sendUpdatedExposeEvent] at /work/build/qt5_workdir/w/s/qtbase/src/plugins/platforms/ios/quiview.mm:183
#20	0x00000001000c3be4 in -[QUIView displayLayer:] at /work/build/qt5_workdir/w/s/qtbase/src/plugins/platforms/ios/quiview.mm:166
#21	0x000000018ad7ad88 in CA::Layer::display() ()
#22	0x000000018ad5c570 in CA::Layer::display_if_needed(CA::Transaction*) ()
#23	0x000000018ad5c228 in CA::Layer::layout_and_display_if_needed(CA::Transaction*) ()
#24	0x000000018ad5ba14 in CA::Context::commit_transaction(CA::Transaction*) ()
#25	0x000000018ad5b798 in CA::Transaction::commit() ()
#26	0x000000018ad551c8 in CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) ()
#27	0x0000000186bbad98 in __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ ()
#28	0x0000000186bb7d24 in __CFRunLoopDoObservers ()
#29	0x0000000186bb8104 in __CFRunLoopRun ()
#30	0x0000000186ae51f4 in CFRunLoopRunSpecific ()
#31	0x00000001000d6dbc in QEventDispatcherCoreFoundation::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) at /work/build/qt5_workdir/w/s/qtbase/src/platformsupport/eventdispatchers/qeventdispatcher_cf.mm:275
#32	0x00000001000b11e8 in QIOSEventDispatcher::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) at /work/build/qt5_workdir/w/s/qtbase/src/plugins/platforms/ios/qioseventdispatcher.mm:479
#33	0x0000000100feb09c in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qeventloop.cpp:128
#34	0x0000000100feb2dc in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qeventloop.cpp:204
#35	0x00000001005bccb4 in QBasicDrag::drag(QDrag*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qsimpledrag.cpp:177
#36	0x00000001005e24e8 in QDragManager::drag(QDrag*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qdnd.cpp:135
#37	0x00000001005e176c in QDrag::exec(QFlags<Qt::DropAction>, Qt::DropAction) at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qdrag.cpp:274
#38	0x00000001005e15e8 in QDrag::exec(QFlags<Qt::DropAction>) at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qdrag.cpp:230
#39	0x00000001004d2798 in QQuickDragAttachedPrivate::startDrag(QFlags<Qt::DropAction>) at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/items/qquickdrag.cpp:725
#40	0x00000001004d239c in QQuickDragAttached::setActive(bool) at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/items/qquickdrag.cpp:305
#41	0x0000000100596fc0 in QQuickDragAttached::qt_metacall(QMetaObject::Call, int, void**) at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/.moc/iphoneos-debug/moc_qquickdrag_p.cpp:753
#42	0x0000000100ff62a0 in QMetaObject::metacall(QObject*, QMetaObject::Call, int, void**) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qmetaobject.cpp:295
#43	0x0000000100b7a278 in QQmlPropertyPrivate::write(QObject*, QQmlPropertyData const&, QVariant const&, QQmlContextData*, QFlags<QQmlPropertyPrivate::WriteFlag>) at /work/build/qt5_workdir/w/s/qtdeclarative/src/qml/qml/qqmlproperty.cpp:1309
#44	0x0000000100b79c78 in QQmlPropertyPrivate::writeValueProperty(QObject*, QQmlPropertyData const&, QVariant const&, QQmlContextData*, QFlags<QQmlPropertyPrivate::WriteFlag>) at /work/build/qt5_workdir/w/s/qtdeclarative/src/qml/qml/qqmlproperty.cpp:1238
#45	0x0000000100b7c2c0 in QQmlPropertyPrivate::writeBinding(QObject*, QQmlPropertyData const&, QQmlContextData*, QQmlJavaScriptExpression*, QV4::ValueRef, bool, QFlags<QQmlPropertyPrivate::WriteFlag>) at /work/build/qt5_workdir/w/s/qtdeclarative/src/qml/qml/qqmlproperty.cpp:1571
#46	0x0000000100c23660 in QQmlBinding::update(QFlags<QQmlPropertyPrivate::WriteFlag>) at /work/build/qt5_workdir/w/s/qtdeclarative/src/qml/qml/qqmlbinding.cpp:223
#47	0x0000000100c72ac4 in QQmlBinding::update() at /work/build/qt5_workdir/w/s/qtdeclarative/src/qml/../../include/QtQml/5.4.1/QtQml/private/../../../../../src/qml/qml/qqmlbinding_p.h:97
#48	0x0000000100c23d20 in QQmlBinding::expressionChanged(QQmlJavaScriptExpression*) at /work/build/qt5_workdir/w/s/qtdeclarative/src/qml/qml/qqmlbinding.cpp:285
#49	0x0000000100c18fb8 in QQmlJavaScriptExpressionGuard_callback(QQmlNotifierEndpoint*, void**) at /work/build/qt5_workdir/w/s/qtdeclarative/src/qml/qml/qqmljavascriptexpression.cpp:363
#50	0x0000000100bf5868 in QQmlNotifier::emitNotify(QQmlNotifierEndpoint*, void**) at /work/build/qt5_workdir/w/s/qtdeclarative/src/qml/qml/qqmlnotifier.cpp:73
#51	0x0000000100b5349c in QQmlData::signalEmitted(QAbstractDeclarativeData*, QObject*, int, void**) at /work/build/qt5_workdir/w/s/qtdeclarative/src/qml/qml/qqmlengine.cpp:715
#52	0x00000001010382bc in QMetaObject::activate(QObject*, int, int, void**) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qobject.cpp:3602
#53	0x0000000101038180 in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qobject.cpp:3582
#54	0x0000000100595cd8 in QQuickDrag::activeChanged() at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/.moc/iphoneos-debug/moc_qquickdrag_p.cpp:444
#55	0x00000001004d3b98 in QQuickDrag::setActive(bool) at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/items/qquickdrag.cpp:922
#56	0x0000000100472754 in QQuickMouseArea::mouseMoveEvent(QMouseEvent*) at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/items/qquickmousearea.cpp:688
#57	0x00000001003a602c in QQuickItem::event(QEvent*) at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/items/qquickitem.cpp:7274
#58	0x0000000100fee8f8 in QCoreApplicationPrivate::notify_helper(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qcoreapplication.cpp:1052
#59	0x0000000100fee85c in QCoreApplication::notify(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qcoreapplication.cpp:997
#60	0x00000001005c2dfc in QGuiApplication::notify(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qguiapplication.cpp:1528
#61	0x0000000100fee6f4 in QCoreApplication::notifyInternal(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qcoreapplication.cpp:935
#62	0x00000001005cb1a8 in QCoreApplication::sendEvent(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:228
#63	0x00000001003b6548 in QQuickWindowPrivate::translateTouchToMouse(QQuickItem*, QTouchEvent*) at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/items/qquickwindow.cpp:593
#64	0x00000001003bd724 in QQuickWindowPrivate::deliverMatchingPointsToItem(QQuickItem*, QTouchEvent*, QSet<int>*, QSet<int> const&, QList<QTouchEvent::TouchPoint> const&, QSet<QQuickItem*>*) at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/items/qquickwindow.cpp:2048
#65	0x00000001003bd310 in QQuickWindowPrivate::deliverTouchPoints(QQuickItem*, QTouchEvent*, QList<QTouchEvent::TouchPoint> const&, QSet<int>*, QHash<QQuickItem*, QList<QTouchEvent::TouchPoint> >*, QSet<QQuickItem*>*) at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/items/qquickwindow.cpp:2006
#66	0x00000001003bcfc8 in QQuickWindowPrivate::deliverTouchPoints(QQuickItem*, QTouchEvent*, QList<QTouchEvent::TouchPoint> const&, QSet<int>*, QHash<QQuickItem*, QList<QTouchEvent::TouchPoint> >*, QSet<QQuickItem*>*) at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/items/qquickwindow.cpp:1956
#67	0x00000001003bcb2c in QQuickWindowPrivate::reallyDeliverTouchEvent(QTouchEvent*) at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/items/qquickwindow.cpp:1911
#68	0x00000001003bcd8c in QQuickWindowPrivate::flushDelayedTouchEvent() at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/items/qquickwindow.cpp:1860
#69	0x0000000100381244 in QSGThreadedRenderLoop::polishAndSync(QSGThreadedRenderLoop::Window*, bool) at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/scenegraph/qsgthreadedrenderloop.cpp:1089
#70	0x0000000100382460 in QSGThreadedRenderLoop::event(QEvent*) at /work/build/qt5_workdir/w/s/qtdeclarative/src/quick/scenegraph/qsgthreadedrenderloop.cpp:1190
#71	0x0000000100fee8f8 in QCoreApplicationPrivate::notify_helper(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qcoreapplication.cpp:1052
#72	0x0000000100fee85c in QCoreApplication::notify(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qcoreapplication.cpp:997
#73	0x00000001005c2dfc in QGuiApplication::notify(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/kernel/qguiapplication.cpp:1528
#74	0x0000000100fee6f4 in QCoreApplication::notifyInternal(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qcoreapplication.cpp:935
#75	0x00000001005cb1a8 in QCoreApplication::sendEvent(QObject*, QEvent*) at /work/build/qt5_workdir/w/s/qtbase/src/gui/../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:228
#76	0x000000010107bd7c in QTimerInfoList::activateTimers() at /work/build/qt5_workdir/w/s/qtbase/src/corelib/kernel/qtimerinfo_unix.cpp:635
#77	0x00000001000d7660 in QEventDispatcherCoreFoundation::processTimers(__CFRunLoopTimer*) at /work/build/qt5_workdir/w/s/qtbase/src/platformsupport/eventdispatchers/qeventdispatcher_cf.mm:422
#78	0x00000001000d7e14 in ___ZN30QEventDispatcherCoreFoundation12updateTimersEv_block_invoke at /work/build/qt5_workdir/w/s/qtbase/src/platformsupport/eventdispatchers/qeventdispatcher_cf.mm:598
#79	0x0000000186bbac20 in __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ ()
#80	0x0000000186bba8d0 in __CFRunLoopDoTimer ()
#81	0x0000000186bb831c in __CFRunLoopRun ()
#82	0x0000000186ae51f4 in CFRunLoopRunSpecific ()
#83	0x000000018ff076fc in GSEventRunModal ()
#84	0x000000018b47610c in UIApplicationMain ()
#85	0x00000001000b14c8 in main at /work/build/qt5_workdir/w/s/qtbase/src/plugins/platforms/ios/qioseventdispatcher.mm:232
#86	0x000000019825ea08 in start ()