From mboxrd@z Thu Jan  1 00:00:00 1970
From: Junio C Hamano <junkio@cox.net>
Subject: Re: How should I handle binary file with GIT
Date: Wed, 05 Apr 2006 13:20:34 -0700
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Cc: "Randal L. Schwartz" <merlyn@stonehenge.com>, git@vger.kernel.org
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To: Nicolas Pitre <nico@cam.org>
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Nicolas Pitre <nico@cam.org> writes:

> On Wed, 5 Apr 2006, Junio C Hamano wrote:
>
>> We've been trying to keep our diff output reversible (e.g. we
>> show what the filemode of the preimage is), so if we take the
>> above route, it probably should record deltas for both going
>> from preimage to postimage _and_ going the other way (unless
>> xdelta can be applied in-reverse, which I do not think is the
>> case).
>
> You cannot reverse a delta.  However if you were able to apply a delta 
> from preimage to postimage that means you must already have had preimage 
> in your object store.  Therefore reverting such a patch would simply 
> involve restoring preimage.

The case I had in mind was where you shipped a tarball of the
tip to somebody (or "a shallow clone"), and after seeing him
having problems with that release, sending him a patch telling
him "reverting this might help, could you please give it a try?"

Of course you could be nicer to him and generate the reverse
diff on your end in such a case instead.