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

[martin rudalics]

> And how would you combine the results? There are filesystems where I can
> delete a file even if I can't write it.

Glenn's patch already throws a file-error when the directory is not
writable.  Hence throwing a file-error when an backup file is not
writable doesn't seem to harm much.  Ulrich mentions a change where the
user wants to back-up to a writable file in a non-writable directory.
Thus it might make sense to first check if the backup file is writable
and check whether the directory is writable iff the backup file is not.