From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?UTF-8?Q?Court=C3=A8s?=)
Subject: bug#22423: git-fetch does not update checked out tree when commit
	hash changes
Date: Thu, 21 Jan 2016 11:10:14 +0100
Message-ID: <87vb6n1bw9.fsf@gnu.org>
References: <20160121065403.GA4278@thebird.nl> <87twm79v05.fsf@gnu.org>
	<20160121090853.GA4914@thebird.nl>
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To: Pjotr Prins <pjotr.public12@thebird.nl>
Cc: 22423-done@debbugs.gnu.org

Pjotr Prins <pjotr.public12@thebird.nl> skribis:

> On Thu, Jan 21, 2016 at 09:50:18AM +0100, Ludovic Court=C3=A8s wrote:
>> This is expected: origins are fixed-output derivations, meaning that it
>> does not matter how we perform them (using Git, over HTTP, or thanks to
>> an avian carrier), as long as the result has the specified sha256.
>>=20
>> Thus, when you change, say, the Git commit ID or origin =E2=80=98method=
=E2=80=99 without
>> changing the =E2=80=98sha256=E2=80=99 field, nothing happens: the daemon=
 says =E2=80=9COK, I
>> already have a store item with that =E2=80=98sha256=E2=80=99, so I don=
=E2=80=99t do anything.=E2=80=9D
>>=20
>> Clearly, one has to be cautious with this, it=E2=80=99s easy to mistaken=
ly use
>> the old source.
>
> Hmmm. I thought the sha256 was calculated over the derivation +
> sources

What you=E2=80=99re saying is true of the hash that appears in /gnu/store f=
ile
name, but I was referring to the =E2=80=98sha256=E2=80=99 field of origins,=
 which is a
different thing.

Ludo=E2=80=99.