message: Remove Neg for BigUint
  A panicking implementation is useless, or worse because it still
  satisfies `T: Neg`. This artifact dates back to when `BigUint` was still
  in the standard library, but the rest of the primitive unsigned `Neg`
  implementations were removed before Rust 1.0.
diff: @@ -12,7 +12,7 @@ use core::iter::{Product, Sum};
  use core::mem;
  use core::ops::{
  Add, AddAssign, BitAnd, BitAndAssign, BitOr, BitOrAssign, BitXor, BitXorAssign, Div, DivAssign,
  - Mul, MulAssign, Neg, Rem, RemAssign, Shl, ShlAssign, Shr, ShrAssign, Sub, SubAssign,
  + Mul, MulAssign, Rem, RemAssign, Shl, ShlAssign, Shr, ShrAssign, Sub, SubAssign,
  };
  use core::str::{self, FromStr};
  use core::{f32, f64};
  @@ -1495,24 +1495,6 @@ impl Rem<BigUint> for u128 {
  }
  }
  -impl Neg for BigUint {
  - type Output = BigUint;
  -
  - #[inline]
  - fn neg(self) -> BigUint {
  - panic!()
  - }
  -}
  -
  -impl<'a> Neg for &'a BigUint {
  - type Output = BigUint;
  -
  - #[inline]
  - fn neg(self) -> BigUint {
  - panic!()
  - }
  -}
  -
  impl CheckedAdd for BigUint {
  #[inline]
  fn checked_add(&self, v: &BigUint) -> Option<BigUint> {
  