qdbusviewer crashes on start if system bus is not available

Thread 3 (Thread 0x7f603a342700 (LWP 114105)):
#0  0x00007f60430ab49d in poll () at /lib64/libc.so.6
#1  0x00007f60401fc432 in  () at /usr/lib64/libxcb.so.1
#2  0x00007f60401fe007 in xcb_wait_for_event () at /usr/lib64/libxcb.so.1
#3  0x00007f603d5d91cd in QXcbEventReader::run() (this=0x1748f80) at /home/thiago/src/qt/qt5/qtbase/src/plugins/platforms/xcb/qxcbconnection.cpp:1313
#4  0x00007f60437bbfb0 in QThreadPrivate::start(void*) (arg=0x1748f80) at /home/thiago/src/qt/qt5/qtbase/src/corelib/thread/qthread_unix.cpp:340
#5  0x00007f6042db44a4 in start_thread () at /lib64/libpthread.so.0
#6  0x00007f60430b3ded in clone () at /lib64/libc.so.6

Thread 2 (Thread 0x7f6044e648c0 (LWP 114104)):
#0  0x00007f60446c120f in QMap<Qt::GestureType, QFlags<Qt::GestureFlag> >::isEmpty() const (this=0x1937f48) at ../../include/QtCore/../../../../../../src/qt/qt5/qtbase/src/corelib/tools/qmap.h:358
#1  0x00007f60446bc7a4 in QGestureManager::filterEvent(QWidget*, QEvent*) (this=0x19e6c70, receiver=0x1928170, event=0x18b6130) at /home/thiago/src/qt/qt5/qtbase/src/widgets/kernel/qgesturemanager.cpp:481
#2  0x00007f6044646b94 in QApplication::notify(QObject*, QEvent*) (this=0x7ffdf64cb230, receiver=0x1928170, e=0x18b6130) at /home/thiago/src/qt/qt5/qtbase/src/widgets/kernel/qapplication.cpp:3101
#3  0x00007f6043a05a88 in QCoreApplication::notifyInternal2(QObject*, QEvent*) (receiver=0x1928170, event=0x18b6130) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qcoreapplication.cpp:1015
#4  0x00007f6043a09ce4 in QCoreApplication::sendEvent(QObject*, QEvent*) (receiver=0x1928170, event=0x18b6130) at ../../include/QtCore/../../../../../../src/qt/qt5/qtbase/src/corelib/kernel/qcoreapplication.h:227
#5  0x00007f6043a06e89 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) (receiver=0x0, event_type=0, data=0x1728150) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qcoreapplication.cpp:1650
#6  0x00007f6043a067fa in QCoreApplication::sendPostedEvents(QObject*, int) (receiver=0x0, event_type=0) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qcoreapplication.cpp:1508
#7  0x00007f6043a86c2e in postEventSourceDispatch(GSource*, GSourceFunc, gpointer) (s=0x1897ac0) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qeventdispatcher_glib.cpp:270
#8  0x00007f60428970c7 in g_main_context_dispatch () at /usr/lib64/libglib-2.0.so.0
#9  0x00007f60428972f8 in  () at /usr/lib64/libglib-2.0.so.0
#10 0x00007f604289739c in g_main_context_iteration () at /usr/lib64/libglib-2.0.so.0
#11 0x00007f6043a873e5 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x172ee40, flags=...) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qeventdispatcher_glib.cpp:417
#12 0x00007f603d64909e in QPAEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x172ee40, flags=...) at /home/thiago/src/qt/qt5/qtbase/src/platformsupport/eventdispatchers/qeventdispatcher_glib.cpp:115
#13 0x00007f6043a01f6e in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x7ffdf64cb0f0, flags=...) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qeventloop.cpp:128
#14 0x00007f6043a0226d in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x7ffdf64cb0f0, flags=...) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qeventloop.cpp:204
#15 0x00007f6043a061d5 in QCoreApplication::exec() () at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qcoreapplication.cpp:1285
#16 0x00007f6043e6e1a2 in QGuiApplication::exec() () at /home/thiago/src/qt/qt5/qtbase/src/gui/kernel/qguiapplication.cpp:1598
#17 0x00007f60446466f1 in QApplication::exec() () at /home/thiago/src/qt/qt5/qtbase/src/widgets/kernel/qapplication.cpp:2971
#18 0x000000000041b89f in main(int, char**) (argc=1, argv=0x7ffdf64cb3e8) at /home/thiago/src/qt/qt5/qttools/src/qdbus/qdbusviewer/main.cpp:63

Thread 1 (Thread 0x7f6032b28700 (LWP 114106)):
#0  0x00007f6042ffec58 in raise () at /lib64/libc.so.6
#1  0x00007f60430000aa in abort () at /lib64/libc.so.6
#2  0x00007f603210fb64 in  () at /lib64/libdbus-1.so.3
#3  0x00007f6032106ce1 in  () at /lib64/libdbus-1.so.3
#4  0x00007f60320ef30c in dbus_connection_dispatch () at /lib64/libdbus-1.so.3
#5  0x00007f6044f385a5 in q_dbus_connection_dispatch(DBusConnection*) (connection=0x0) at /home/thiago/src/qt/qt5/qtbase/src/dbus/qdbus_symbols_p.h:189
#6  0x00007f6044f3deac in QDBusConnectionPrivate::doDispatch() (this=0x7f602c004480) at /home/thiago/src/qt/qt5/qtbase/src/dbus/qdbusintegrator.cpp:1110
#7  0x00007f6044f5494e in QtPrivate::FunctorCall<QtPrivate::IndexesList<>, QtPrivate::List<>, void, void (QDBusConnectionPrivate::*)()>::call(void (QDBusConnectionPrivate::*)(), QDBusConnectionPrivate*, void**) (f=(void (QDBusConnectionPrivate::*)(QDBusConnectionPrivate * const)) 0x7f6044f3de4a <QDBusConnectionPrivate::doDispatch()>, o=0x7f602c004480, arg=0x19f0fd0) at ../../include/QtCore/../../../../../../src/qt/qt5/qtbase/src/corelib/kernel/qobjectdefs_impl.h:501
#8  0x00007f6044f53f97 in QtPrivate::FunctionPointer<void (QDBusConnectionPrivate::*)()>::call<QtPrivate::List<>, void>(void (QDBusConnectionPrivate::*)(), QDBusConnectionPrivate*, void**) (f=(void (QDBusConnectionPrivate::*)(QDBusConnectionPrivate * const)) 0x7f6044f3de4a <QDBusConnectionPrivate::doDispatch()>, o=0x7f602c004480, arg=0x19f0fd0) at ../../include/QtCore/../../../../../../src/qt/qt5/qtbase/src/corelib/kernel/qobjectdefs_impl.h:520
#9  0x00007f6044f518d6 in QtPrivate::QSlotObject<void (QDBusConnectionPrivate::*)(), QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*, void**, bool*) (which=1, this_=0x7f602c00a630, r=0x7f602c004480, a=0x19f0fd0, ret=0x0) at ../../include/QtCore/../../../../../../src/qt/qt5/qtbase/src/corelib/kernel/qobject_impl.h:143
#10 0x00007f6043a4e719 in QtPrivate::QSlotObjectBase::call(QObject*, void**) (this=0x7f602c00a630, r=0x7f602c004480, a=0x19f0fd0) at ../../include/QtCore/../../../../../../src/qt/qt5/qtbase/src/corelib/kernel/qobject_impl.h:124
#11 0x00007f6043a43a25 in QMetaCallEvent::placeMetaCall(QObject*) (this=0x19ec250, object=0x7f602c004480) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qobject.cpp:493
#12 0x00007f6043a44af2 in QObject::event(QEvent*) (this=0x7f602c004480, e=0x19ec250) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qobject.cpp:1256
#13 0x00007f6043a05f02 in QCoreApplicationPrivate::notify_helper(QObject*, QEvent*) (receiver=0x7f602c004480, event=0x19ec250) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qcoreapplication.cpp:1149
#14 0x00007f6043a05b85 in doNotify(QObject*, QEvent*) (receiver=0x7f602c004480, event=0x19ec250) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qcoreapplication.cpp:1090
#15 0x00007f6043a05a59 in QCoreApplication::notifyInternal2(QObject*, QEvent*) (receiver=0x7f602c004480, event=0x19ec250) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qcoreapplication.cpp:1014
#16 0x00007f6043a09ce4 in QCoreApplication::sendEvent(QObject*, QEvent*) (receiver=0x7f602c004480, event=0x19ec250) at ../../include/QtCore/../../../../../../src/qt/qt5/qtbase/src/corelib/kernel/qcoreapplication.h:227
#17 0x00007f6043a06e89 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) (receiver=0x0, event_type=0, data=0x18a6e80) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qcoreapplication.cpp:1650
#18 0x00007f6043a067fa in QCoreApplication::sendPostedEvents(QObject*, int) (receiver=0x0, event_type=0) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qcoreapplication.cpp:1508
#19 0x00007f6043a86c2e in postEventSourceDispatch(GSource*, GSourceFunc, gpointer) (s=0x7f602c0012d0) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qeventdispatcher_glib.cpp:270
#20 0x00007f60428970c7 in g_main_context_dispatch () at /usr/lib64/libglib-2.0.so.0
#21 0x00007f60428972f8 in  () at /usr/lib64/libglib-2.0.so.0
#22 0x00007f604289739c in g_main_context_iteration () at /usr/lib64/libglib-2.0.so.0
#23 0x00007f6043a87414 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x7f602c0008c0, flags=...) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qeventdispatcher_glib.cpp:419
#24 0x00007f6043a01f6e in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x7f6032b27c40, flags=...) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qeventloop.cpp:128
#25 0x00007f6043a0226d in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x7f6032b27c40, flags=...) at /home/thiago/src/qt/qt5/qtbase/src/corelib/kernel/qeventloop.cpp:204
#26 0x00007f60437b28a5 in QThread::exec() (this=0x7f6044fded80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at /home/thiago/src/qt/qt5/qtbase/src/corelib/thread/qthread.cpp:503
#27 0x00007f6044f2e02e in QDBusConnectionManager::run() (this=0x7f6044fded80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at /home/thiago/src/qt/qt5/qtbase/src/dbus/qdbusconnection.cpp:177
#28 0x00007f60437bbfb0 in QThreadPrivate::start(void*) (arg=0x7f6044fded80 <(anonymous namespace)::Q_QGS__q_manager::innerFunction()::holder>) at /home/thiago/src/qt/qt5/qtbase/src/corelib/thread/qthread_unix.cpp:340
#29 0x00007f6042db44a4 in start_thread () at /lib64/libpthread.so.0
#30 0x00007f60430b3ded in clone () at /lib64/libc.so.6

$ DBUS_SYSTEM_BUS_ADDRESS=unix:path=/dev/null qdbusviewer