From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeff King <peff@peff.net>
Subject: Re: [PATCH] repack.c: rename and unlink pack file if it exists
Date: Wed, 5 Feb 2014 15:37:40 -0500
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Cc: Stefan Beller <stefanbeller@googlemail.com>,
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To: Junio C Hamano <gitster@pobox.com>
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On Wed, Feb 05, 2014 at 12:31:34PM -0800, Junio C Hamano wrote:

> Jeff King <peff@peff.net> writes:
> 
> > The minimal fix you posted below does make sense to me as a stopgap, and
> > we can look into dropping the code entirely during the next cycle. It
> > would be nice to have a test to cover this case, though.
> 
> Sounds sensible.  Run "repack -a -d" once, and then another while
> forcing it to be single threaded, or something?

Certainly that's the way to trigger the code, but doing this:

diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
index b45bd1e..6647ba1 100755
--- a/t/t7700-repack.sh
+++ b/t/t7700-repack.sh
@@ -162,7 +162,12 @@ test_expect_success 'objects made unreachable by grafts only are kept' '
 	git reflog expire --expire=$test_tick --expire-unreachable=$test_tick --all &&
 	git repack -a -d &&
 	git cat-file -t $H1
-	'
+'
+
+test_expect_success 'repack can handle generating the same pack again' '
+	git -c pack.threads=1 repack -ad &&
+	git -c pack.threads=1 repack -ad
+'
 
 test_done
 

...does not seem to fail, and it does not seem to leave any cruft in
place. So maybe I am misunderstanding the thing the patch is meant to
fix. Is it that we simply do not replace the pack in this instance?

I guess we would have to generate a pack with the identical set of
objects, then, but somehow different in its pack parameters (perhaps
turning off deltas?).

-Peff