[Boost-users] [boost] [containers] wrong flat_xxx::insert(ordered_unique_range_t, first, last) ?

Hi there, Say, if I have a set A{0, 1} and now I insert B{0.2, 0.8} into A, using that function, I'd expect A{0, 0.2, 0.8, 1}, but what I really get is A{0, 1}; If A is {0, 0.1}, I'll get A{0, 0.1, 0.2, 0.8} as expected... So it looks like that insert(ordered_unique_range_t...) can only insert elements subsequent to A. If this is the expected behavior, this function is useless to me, or is it a bug? File attached. Thanks.