Re: backup-buffer-copy loops if old backup can't be deleted

[Richard Stallman]

    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.

That sounds like a good reason.