Useless warning

This sign, seen on the B3159 near Martinstown, just outside Dorchester, is apparently not quite as stupid as it looks, since it was actually a temporary notice referring to an out-of-action electronic signboard (not visible in the photograph) just before a sharp bend in the road. 

But, when you think about it, it is still stupid. Wouldn't it have made more sense to erect a temporary sign saying "Caution: sharp bend"?