Make sure we use dnd position if available. Fixes bug 1410843.

Fixes: https://launchpad.net/bugs/1410843

openlp/core/ui/servicemanager.py

@@ -1396,6 +1396,7 @@ class ServiceManager(OpenLPMixin, RegistryMixin, QtGui.QWidget, Ui_ServiceManage
         if expand is None:
             expand = Settings().value('advanced/expand service item')
         item.from_service = True
+        if position != -1:
             self.drop_position = position
         if replace:
             s_item, child = self.find_service_item()