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From: Richard Stallman <rms@gnu.org>
Newsgroups: gmane.emacs.bugs
Subject: Re: backup-buffer-copy loops if old backup can't be deleted
Date: Thu, 23 Aug 2007 16:59:49 -0400
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To: Martin von Gagern <Martin.vGagern@gmx.net>, bug-gnu-emacs@gnu.org
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In-reply-to: <46CAD810.3050904@gmx.net> (message from Martin von Gagern on
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    -		       (condition-case nil
    -			   (delete-file to-name)
    -			 (file-error nil))
    +		       (and (file-exists-p to-name)
    +			    (delete-file to-name))

I think that fix is actually correct.
It is copy-file that detects the race condition.
As long as copy-file is inside a loop, creation of
the file by another process will be dealt with.

So this change should be installed.

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