message: Haiku: skip renaming if filenames are the same
diff: @@ -369,7 +369,7 @@ fn rustc(cx: &mut Context, unit: &Unit, exec: Arc<Executor>) -> CargoResult<Work
  let src = dst.with_file_name(dst.file_name().unwrap()
  .to_str().unwrap()
  .replace(&real_name, &crate_name));
  - if src.exists() {
  + if src.exists() && src.file_name() != dst.file_name() {
  fs::rename(&src, &dst).chain_error(|| {
  internal(format!("could not rename crate {:?}", src))
  })?;
  