Guard code to avoid deleting a turn twice (see #4968, #4928)
Guard code to avoid deleting a turn twice
(see #4968, #4928)

AndreasHae/iD,kartta-labs/iD,openstreetmap/iD,AndreasHae/iD,mapmeld/iD,morray/iD,AndreasHae/iD,ngageoint/hootenanny-ui,digidem/iD,ngageoint/hootenanny-ui,kartta-labs/iD,mapmeld/iD,morray/iD,ngageoint/hootenanny-ui,openstreetmap/iD,mapmeld/iD,kartta-labs/iD,openstreetmap/iD,digidem/iD