[BUG] Can't remove unsatisfiable constraint

[romannep]

Reproducible example

    final a = Param();
    final b = Param();
    final c1 = a >= cm(10);
    final c2 = b <= cm(5);
    final c3 = b >= a;

    final solver = Solver();
    print('add c1 ${solver.addConstraint(c1).message}');
    print('add c2 ${solver.addConstraint(c2).message}');
    print('add c3 ${solver.addConstraint(c3).message}');
    print('remove c3 ${solver.removeConstraint(c3).message}');
    solver1.flushUpdates();
    print('vars a=${a.value} b=${b.value}');

Output

add c1 Success
add c2 Success
add c3 Unsatisfiable constraint
remove c3 Unknown constraint
vars a=10 b=10

Solver says "Unknown constraint" on removing c3 constraint, but c3 constraint has an impact on the solution.

[domesticmouse]

#13 has been published as 0.4.1 - https://pub.dev/packages/cassowary/changelog