Crash when deleting kits

1. Have two kits configured in Creator.
2. Create a new project and configure it to use both kits.
3. Go to "Tools" -> "Options..." > "Build & Run" -> "Kits".
4. Select the default kit and click "Remove".
5. Select the other kit and click "Remove".
6. Click "Apply".
   Creator crashes:

   1   QtSharedPointer::ExternalRefCountData::getAndRef                                                                                                                                           qsharedpointer.cpp        1335 0x7ffff62c95c1 
   2   QWeakPointer<QObject>::QWeakPointer<QObject>                                                                                                                                               qsharedpointer_impl.h     723  0x7fffdff613f6 
   3   QWeakPointer<QObject>::assign<QObject>                                                                                                                                                     qsharedpointer_impl.h     719  0x7fffdff6076a 
   4   QPointer<ProjectExplorer::Target>::operator=                                                                                                                                               qpointer.h                83   0x7fffdffd716b 
   5   Debugger::Internal::DebuggerPluginPrivate::updateUiForTarget                                                                                                                               debuggerplugin.cpp        3349 0x7fffdffc6b6c 
   6   QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<ProjectExplorer::Target *>, void, void (Debugger::Internal::DebuggerPluginPrivate:: *)(ProjectExplorer::Target *)>::call qobjectdefs_impl.h        141  0x7fffdffe1c43 
   7   QtPrivate::FunctionPointer<void (Debugger::Internal::DebuggerPluginPrivate:: *)(ProjectExplorer::Target *)>::call<QtPrivate::List<ProjectExplorer::Target *>, void>                        qobjectdefs_impl.h        160  0x7fffdffe0604 
   8   QtPrivate::QSlotObject<void (Debugger::Internal::DebuggerPluginPrivate:: *)(ProjectExplorer::Target *), QtPrivate::List<ProjectExplorer::Target *>, void>::impl                            qobject_impl.h            120  0x7fffdffdeafa 
   9   QtPrivate::QSlotObjectBase::call                                                                                                                                                           qobject_impl.h            101  0x7ffff649fbcb 
   10  QMetaCallEvent::placeMetaCall                                                                                                                                                              qobject.cpp               500  0x7ffff64947f9 
   11  QObject::event                                                                                                                                                                             qobject.cpp               1263 0x7ffff6495a35 
   12  QApplicationPrivate::notify_helper                                                                                                                                                         qapplication.cpp          3799 0x7ffff6fba9aa 
   13  QApplication::notify                                                                                                                                                                       qapplication.cpp          3159 0x7ffff6fb7bf8 
   14  QCoreApplication::notifyInternal2                                                                                                                                                          qcoreapplication.cpp      988  0x7ffff6457067 
   15  QCoreApplication::sendEvent                                                                                                                                                                qcoreapplication.h        231  0x7ffff645b3ca 
   16  QCoreApplicationPrivate::sendPostedEvents                                                                                                                                                  qcoreapplication.cpp      1649 0x7ffff6458582 
   17  QCoreApplication::sendPostedEvents                                                                                                                                                         qcoreapplication.cpp      1503 0x7ffff6457ed8 
   18  postEventSourceDispatch                                                                                                                                                                    qeventdispatcher_glib.cpp 276  0x7ffff64dd733 
   19  g_main_dispatch                                                                                                                                                                            gmain.c                   3154 0x7ffff3158197 
   20  g_main_context_dispatch                                                                                                                                                                    gmain.c                   3769 0x7ffff3158197 
   ... <Mehr>                                                                                                                                                                                                                                   
   

Creator should never crash.