MinniZinc 2.6.3: flattener error (wrong answer)

[matsc-at-sics-se]

This is a continuation of #565 , which apparently was not quite fixed. This model is infeasible:

var bool: c;
var bool: d;
constraint
    not(not(true xor c) -> ((d -> c) xor false));

output [show([c,d]) ++ "\n"];

but MiniZinc finds two wrong answers:

$ minizinc -a bar.mzn
[true, false]
----------
[true, true]
----------
==========

[Dekker1]

It appears that this issue has already been resolved on the current develop branch. I've added an additional regression test in 4b297c93254c86337c019fd47d8be341b96e600a to ensure the issue doesn't reappear.

[cyderize]

This should now be fixed in version 2.7.0