message: Distribute EnabledIf across Expr::monomials
diff: @@ -1836,11 +1836,11 @@ impl<F: Neg<Output = F> + Clone + One + Zero + PartialEq> Expr<F> {
  mul_monomials(&x, &x)
  }
  EnabledIf(feature, x) => {
  - if feature.is_enabled() {
  - x.monomials(ev)
  - } else {
  - HashMap::default()
  - }
  + let e = x.monomials(ev);
  + HashMap::from_iter(
  + e.into_iter()
  + .map(|(m, c)| (m, Expr::EnabledIf(*feature, Box::new(c)))),
  + )
  }
  }
  }
  