Bug in IBEX arithmetic

[SimonRohou]

Hello the IBEX Team,

Here is something strange:

  Interval a = Interval(3,8);
  Interval b = Interval(1,3) & Interval(6,7); // [b] is empty
  Interval c = a+b;
  cout << "c=[3,8]+([1,3]∩[6,7]): " << c << endl;

Result:
c=[3,8]+([1,3]∩[6,7]): [9, 11]

[gchabert]

oh my god... I wonder how is it possible that a bug like this stays invisible so long.
Maybe because people don't use that much operator&.
Well, that was actually a bug in gaol... but I've wrapped it so now it is fixed (in develop).