Clear related sale when duplicating an opportunity

issue4287
review7671002
(grafted from 7de84951e9a6b8e5f493aab6dca4fce0b8ee1c99)

--HG--
branch : 3.4
extra : source : 7de84951e9a6b8e5f493aab6dca4fce0b8ee1c99