Regression: Designer crashes on exit

1  QListData::size                                                                                                                                                                      qlist.h                  113  0x426898       
2  QList<QDesignerFormWindow *>::count                                                                                                                                                  qlist.h                  342  0x44551c       
3  QDesignerWorkbench::formWindowCount                                                                                                                                                  qdesigner_workbench.cpp  556  0x44161c       
4  QDesignerFormWindow::getNumberOfUntitledWindows                                                                                                                                      qdesigner_formwindow.cpp 158  0x43d37b       
5  QDesignerFormWindow::updateWindowTitle                                                                                                                                               qdesigner_formwindow.cpp 197  0x43d6a9       
6  QDesignerFormWindow::updateChanged                                                                                                                                                   qdesigner_formwindow.cpp 247  0x43dc9b       
7  QtPrivate::FunctorCall<QtPrivate::IndexesList<>, QtPrivate::List<>, void, void (QDesignerFormWindow:: *)()>::call(void (QDesignerFormWindow:: *)(), QDesignerFormWindow *, void * *) qobjectdefs_impl.h       143  0x43e8df       
8  QtPrivate::FunctionPointer<void (QDesignerFormWindow:: *)()>::call<QtPrivate::List<>, void>(void (QDesignerFormWindow:: *)(), QDesignerFormWindow *, void * *)                       qobjectdefs_impl.h       162  0x43e82c       
9  QtPrivate::QSlotObject<void (QDesignerFormWindow:: *)(), QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase *, QObject *, void * *, bool *)                              qobject_impl.h           120  0x43e6b2       
10 QtPrivate::QSlotObjectBase::call                                                                                                                                                     qobject_impl.h           101  0x7ffff5faab23 
11 QMetaObject::activate                                                                                                                                                                qobject.cpp              3723 0x7ffff5fa7a25 
12 QMetaObject::activate                                                                                                                                                                qobject.cpp              3602 0x7ffff5fa7344 
13 QUndoStack::indexChanged                                                                                                                                                             moc_qundostack.cpp       267  0x7ffff71d1cc0 
14 QUndoStack::clear                                                                                                                                                                    qundostack.cpp           547  0x7ffff71d01ac 
15 QUndoStack::~QUndoStack                                                                                                                                                              qundostack.cpp           515  0x7ffff71d00d0 
16 qdesigner_internal::FormWindow::~FormWindow                                                                                                                                          formwindow.cpp           314  0x7ffff7c01b59 
17 qdesigner_internal::FormWindow::~FormWindow                                                                                                                                          formwindow.cpp           332  0x7ffff7c01bc2 
18 qDeleteAll<QList<qdesigner_internal::FormWindow *>::const_iterator>                                                                                                                  qalgorithms.h            317  0x7ffff7c25caa 
19 qDeleteAll<QList<qdesigner_internal::FormWindow *>>                                                                                                                                  qalgorithms.h            325  0x7ffff7c24d20 
20 qdesigner_internal::FormWindowManager::~FormWindowManager                                                                                                                            formwindowmanager.cpp    118  0x7ffff7c1ddbe 
21 qdesigner_internal::FormWindowManager::~FormWindowManager                                                                                                                            formwindowmanager.cpp    119  0x7ffff7c1ddf6 
22 QDesignerFormEditorInterfacePrivate::~QDesignerFormEditorInterfacePrivate                                                                                                            abstractformeditor.cpp   116  0x7ffff74fc8d3 
23 QScopedPointerDeleter<QDesignerFormEditorInterfacePrivate>::cleanup                                                                                                                  qscopedpointer.h         60   0x7ffff74fe0d9 
24 QScopedPointer<QDesignerFormEditorInterfacePrivate, QScopedPointerDeleter<QDesignerFormEditorInterfacePrivate>>::~QScopedPointer                                                     qscopedpointer.h         107  0x7ffff74fda1d 
25 QDesignerFormEditorInterface::~QDesignerFormEditorInterface                                                                                                                          abstractformeditor.cpp   181  0x7ffff74fcb2e 
26 qdesigner_internal::FormEditor::~FormEditor                                                                                                                                          formeditor.cpp           150  0x7ffff7c27854 
27 qdesigner_internal::FormEditor::~FormEditor                                                                                                                                          formeditor.cpp           152  0x7ffff7c27870 
28 QObjectPrivate::deleteChildren                                                                                                                                                       qobject.cpp              1970 0x7ffff5fa2710 
29 QObject::~QObject                                                                                                                                                                    qobject.cpp              1041 0x7ffff5fa0d2d 
30 QDesignerWorkbench::~QDesignerWorkbench                                                                                                                                              qdesigner_workbench.cpp  252  0x43fb50       
31 QDesignerWorkbench::~QDesignerWorkbench                                                                                                                                              qdesigner_workbench.cpp  263  0x43fb6c       
32 QDesigner::~QDesigner                                                                                                                                                                qdesigner.cpp            94   0x43797d       
33 main                                                                                                                                                                                 main.cpp                 41   0x4375ff