833. Every alienation by the testator of the right of ownership in the thing bequeathed, even in a case of necessity, or by forced means, or with right of redemption reserved, or by exchange, carries with it, unless he or she has otherwise provided, a revocation of the will or legacy for all that has been thus disposed of, even though, if it were voluntary, the alienation be void. But a will or legacy is held to affect property which, though alienated by the testator subsequently to the will, is owned by him or her and in his or her possession at his or her death.