message: let's call this a redundant reborrow
diff: @@ -337,7 +337,7 @@ impl<'tcx> Stacks {
  // the stack than the one we come from, just use that.
  // IOW, we check if `new_bor` *already* is "derived from" `ptr.tag`.
  // This also checks frozenness, if required.
  - let bor_already_happened = match (ptr_idx, stack.deref(new_bor, new_kind)) {
  + let bor_redundant = match (ptr_idx, stack.deref(new_bor, new_kind)) {
  // If the new borrow works with the frozen item, or else if it lives
  // above the old one in the stack, our job here is done.
  (_, Ok(None)) => true,
  @@ -345,9 +345,9 @@ impl<'tcx> Stacks {
  // Otherwise we need to create a new borrow.
  _ => false,
  };
  - if bor_already_happened {
  + if bor_redundant {
  assert!(new_bor.is_shared(), "A unique reborrow can never be redundant");
  - trace!("Reborrow is a NOP");
  + trace!("reborrow is redundant");
  continue;
  }
  // We need to do some actual work.
  