Re: [PATCH 3/3] difftool: handle modified symlinks in dir-diff mode

> Detect the null object ID for symlinks in dir-diff so that difftool can
> detect when symlinks are modified in the worktree.
> 
> Previously, a null symlink object ID would crash difftool.
> Handle null object IDs as unknown content that must be read from
> the worktree.
> 
> Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> Signed-off-by: David Aguilar <davvid@gmail.com>
> ---
> This was reworked a bit since the original patch.
> The subject line changed, a lot of comments were added,
> and the tests were made more extensive.
> 
> This implementation is simpler since we now use a get_symlink()
> function in one place and simply skip the problematic code path
> that does not apply to symlinks.  Existing code handles writing
> the symlink content so write_symlink_file() from the original
> patch is gone.