Marble crashes when I reverse empty preview route

Reproducible: Always

Steps to Reproduce:
1. Clear "From" and "To" fields at the "Routing" panel.
2. Launch route preview.
3. Reverse it.

Actual Results:  
Marble crashes


Backtrace:

#0  Marble::GeoDataTreeModel::removeFeature (this=0x7adc00, feature=feature@entry=0x1bd0738) at /home/sergobot/marble/sources/src/lib/marble/GeoDataTreeModel.cpp:845
#1  0x00007ffff66ccbc5 in Marble::GeoDataTreeModel::removeDocument (this=<optimized out>, document=document@entry=0x1bd0730)
    at /home/sergobot/marble/sources/src/lib/marble/GeoDataTreeModel.cpp:876
#2  0x00007ffff67ce24d in Marble::RoutingWidget::clearTour (this=this@entry=0xd13070) at /home/sergobot/marble/sources/src/lib/marble/routing/RoutingWidget.cpp:992
#3  0x00007ffff67ce2e8 in Marble::RoutingWidget::updateRouteState (this=0xd13070, state=Marble::RoutingManager::Retrieved)
    at /home/sergobot/marble/sources/src/lib/marble/routing/RoutingWidget.cpp:580
#4  0x00007ffff7a86a7a in QMetaObject::activate (sender=sender@entry=0x7b0c80, m=m@entry=0x7ffff6c1a840 <Marble::RoutingManager::staticMetaObject>, 
    local_signal_index=local_signal_index@entry=0, argv=argv@entry=0x7fffffffc930) at kernel/qobject.cpp:3567
#5  0x00007ffff67bd21e in Marble::RoutingManager::stateChanged (this=this@entry=0x7b0c80, _t1=Marble::RoutingManager::Retrieved)
    at /home/sergobot/marble/build/src/lib/marble/RoutingManager.moc:164
#6  0x00007ffff67c0c0f in Marble::RoutingManager::retrieveRoute (this=0x7b0c80) at /home/sergobot/marble/sources/src/lib/marble/routing/RoutingManager.cpp:320
#7  0x00007ffff7a86a7a in QMetaObject::activate (sender=sender@entry=0xd29260, m=m@entry=0x7ffff78e18e0 <QAbstractButton::staticMetaObject>, 
    local_signal_index=local_signal_index@entry=2, argv=argv@entry=0x7fffffffcab0) at kernel/qobject.cpp:3567
#8  0x00007ffff7457f32 in QAbstractButton::clicked (this=this@entry=0xd29260, _t1=false) at .moc/release-shared/moc_qabstractbutton.cpp:219
#9  0x00007ffff71b8bf3 in QAbstractButtonPrivate::emitClicked (this=this@entry=0xd29720) at widgets/qabstractbutton.cpp:548
#10 0x00007ffff71b9de0 in QAbstractButtonPrivate::click (this=this@entry=0xd29720) at widgets/qabstractbutton.cpp:541
#11 0x00007ffff71b9ed4 in QAbstractButton::mouseReleaseEvent (this=0xd29260, e=0x7fffffffcf50) at widgets/qabstractbutton.cpp:1123
#12 0x00007ffff727132a in QToolButton::mouseReleaseEvent (this=<optimized out>, e=<optimized out>) at widgets/qtoolbutton.cpp:723
#13 0x00007ffff6e4ece8 in QWidget::event (this=0x1bd0738, event=0x1bd0738) at kernel/qwidget.cpp:8775
#14 0x00007ffff6dff11c in QApplicationPrivate::notify_helper (this=this@entry=0x6c0170, receiver=receiver@entry=0xd29260, e=e@entry=0x7fffffffcf50) at kernel/qapplication.cpp:4570
#15 0x00007ffff6e059be in QApplication::notify (this=<optimized out>, receiver=0xd29260, e=0x7fffffffcf50) at kernel/qapplication.cpp:4113
#16 0x00007ffff7a7286d in QCoreApplication::notifyInternal (this=0x7fffffffdb80, receiver=receiver@entry=0xd29260, event=event@entry=0x7fffffffcf50)
    at kernel/qcoreapplication.cpp:953
#17 0x00007ffff6e0507f in sendEvent (event=<optimized out>, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:231
#18 QApplicationPrivate::sendMouseEvent (receiver=receiver@entry=0xd29260, event=event@entry=0x7fffffffcf50, alienWidget=alienWidget@entry=0xd29260, 
    nativeWidget=nativeWidget@entry=0x734490, buttonDown=buttonDown@entry=0x7ffff78f3578 <qt_button_down>, lastMouseReceiver=..., spontaneous=true) at kernel/qapplication.cpp:3178
#19 0x00007ffff6e7abde in QETWidget::translateMouseEvent (this=this@entry=0x734490, event=event@entry=0x7fffffffd2b0) at kernel/qapplication_x11.cpp:4634
#20 0x00007ffff6e7a477 in QApplication::x11ProcessEvent (this=0x7fffffffdb80, event=event@entry=0x7fffffffd2b0) at kernel/qapplication_x11.cpp:3627
#21 0x00007ffff6ea2432 in x11EventSourceDispatch (s=0x6bca90, callback=0x0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#22 0x00007ffff4e75c5d in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#23 0x00007ffff4e75f48 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#24 0x00007ffff4e75ffc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#25 0x00007ffff7aa0031 in QEventDispatcherGlib::processEvents (this=0x6bc3c0, flags=...) at kernel/qeventdispatcher_glib.cpp:434
#26 0x00007ffff6ea24e6 in QGuiEventDispatcherGlib::processEvents (this=<optimized out>, flags=...) at kernel/qguieventdispatcher_glib.cpp:204
#27 0x00007ffff7a714f1 in QEventLoop::processEvents (this=this@entry=0x7fffffffd690, flags=...) at kernel/qeventloop.cpp:149
#28 0x00007ffff7a71805 in QEventLoop::exec (this=this@entry=0x7fffffffd690, flags=...) at kernel/qeventloop.cpp:204
#29 0x00007ffff7a76f67 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1225
#30 0x0000000000425949 in main (argc=2, argv=0x7fffffffdd38) at /home/sergobot/marble/sources/src/apps/marble-qt/qtmain.cpp:258