'Test interaction of caching with changing constraints.'

def test_change_constraints(self):

    prob = Problem(Minimize(self.a), [(self.a == 2), (self.a >= 1)])
    prob.solve()
    self.assertAlmostEqual(prob.value, 2)
    prob.constraints[0] = (self.a == 1)
    prob.solve()
    self.assertAlmostEqual(prob.value, 1)
