message: Fixed miri stacked borrow violation
diff: @@ -441,8 +441,9 @@ fn index_twice<T>(slc: &mut [T], a: usize, b: usize) -> Pair<&mut T> {
  } else {
  // safe because a, b are in bounds and distinct
  unsafe {
  - let ar = &mut *(slc.get_unchecked_mut(a) as *mut _);
  - let br = &mut *(slc.get_unchecked_mut(b) as *mut _);
  + let ptr = slc.as_mut_ptr();
  + let ar = &mut *ptr.offset(a as isize);
  + let br = &mut *ptr.offset(b as isize);
  Pair::Both(ar, br)
  }
  }
  