Richard Stallman wrote:
> I think there is no need to explicitly check whether the directory
> is writable.  What would be the purpose of that?

I didn't write that patch, but I guess there could be a purpose for it.
Namely it could help deleting a file in vain. If there are Filesystems
that let you delete a writable file even though you can't create new
ones in a non-writable dir, then without those lines, emacs would delete
an old backup only to find out that it can't create a new one.

Most likely these would be cases where the old backup file was writable,
so if you had some logic to write to existing files and only delete them
if they are not writable, then the check whether the directory is
writable should really be superfluous. Otherwise I'm not so sure.

Greetings,
 Martin von Gagern