t / t4013 / diff.diff_--no-index_--raw_--no-abbrev_dir2_diron commit dir: convert read_skip_worktree_file_from_index to take an index (6f52b74)
   1$ git diff --no-index --raw --no-abbrev dir2 dir
   2:000000 100644 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 A      dir/sub
   3$