Add session.begin to fix adding a traffic group
Add session.begin to fix adding a traffic group

agdsn/pycroft,lukasjuhrich/pycroft,agdsn/pycroft,lukasjuhrich/pycroft,agdsn/pycroft,agdsn/pycroft,agdsn/pycroft,lukasjuhrich/pycroft,lukasjuhrich/pycroft