message: Fix the assumption of extern crate prelude
diff: @@ -54,6 +54,8 @@ impl<R: Rng + ?Sized> RandBigInt for R {
  #[cfg(u64_digit)]
  fn gen_biguint(&mut self, bit_size: usize) -> BigUint {
  + use std::slice;
  +
  let (digits, rem) = bit_size.div_rem(&32);
  let native_digits = bit_size.div_ceil(&64);
  let mut data = vec![0u64; native_digits];
  @@ -62,7 +64,7 @@ impl<R: Rng + ?Sized> RandBigInt for R {
  let ptr = data.as_mut_ptr() as *mut u32;
  let len = digits + (rem > 0) as usize;
  debug_assert!(native_digits * 2 >= len);
  - let data = std::slice::from_raw_parts_mut(ptr, len);
  + let data = slice::from_raw_parts_mut(ptr, len);
  gen_bits(self, data, rem);
  }
  #[cfg(target_endian = "big")]
  