message: smt: fix unsounded in fold introduced in last commit
diff: @@ -1029,7 +1029,8 @@ expr expr::cmp_eq(const expr &rhs, bool simplify) const {
  {
  expr lhs_a, lhs_b, rhs_a, rhs_b;
  - if (isEq(lhs_a, lhs_b) && rhs.isEq(rhs_a, rhs_b) && lhs_a.eq(rhs_a))
  + if (isEq(lhs_a, lhs_b) && lhs_a.bits() == 1 && rhs.isEq(rhs_a, rhs_b) &&
  + lhs_a.eq(rhs_a))
  return lhs_b == rhs_b;
  }
  