Fix change_connection by conn -> old_conn
Fix change_connection by conn -> old_conn

Not sure this code path is ever hit currently since we have factored
everything to add/delete, but keeping in just in case

minesense/VisTrails,VisTrails/VisTrails,VisTrails/VisTrails,minesense/VisTrails,Nikea/VisTrails,minesense/VisTrails,Nikea/VisTrails,hjanime/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,minesense/VisTrails,hjanime/VisTrails,Nikea/VisTrails,celiafish/VisTrails,minesense/VisTrails,VisTrails/VisTrails,hjanime/VisTrails,hjanime/VisTrails,hjanime/VisTrails,celiafish/VisTrails,VisTrails/VisTrails,celiafish/VisTrails,Nikea/VisTrails