allow for graceful merge of cube_join and model_join; model_join may be absent and that's ok
allow for graceful merge of cube_join and model_join; model_join may be
absent and that's ok

zejn/cubes,ubreddy/cubes,she11c0de/cubes,pombredanne/cubes,cesarmarinhorj/cubes,jell0720/cubes,she11c0de/cubes,pombredanne/cubes,she11c0de/cubes,cesarmarinhorj/cubes,ubreddy/cubes,noyeitan/cubes,cesarmarinhorj/cubes,noyeitan/cubes,zejn/cubes,zejn/cubes,jell0720/cubes,ubreddy/cubes,noyeitan/cubes,jell0720/cubes,pombredanne/cubes