Re: Have git SHA1 ID's changed in the last 5 years?

[David Kastrup]

Mark Polesky <address@hidden> writes:

> David Kastrup wrote:
>> but in my repository no commits authored by fred,
>
> Really?  Can you try
> a281aedda8d5ea550f8b851822315cf154acee52 ?

commit a281aedda8d5ea550f8b851822315cf154acee52
Author: fred <fred>
Date:   Wed Mar 27 02:56:08 2002 +0000

    lilypond-1.5.47

But if I do

git log --reverse a281aedda8d5ea550f8b851822315cf154acee52..origin

the list starts with
commit 4f4ad24a3bfeb77cfd0ecca104319607bfd28a63
Author: Han-Wen Nienhuys <address@hidden>
Date:   Wed Oct 9 14:04:46 1996 +0100

    Initial.

commit 675bd3e6ea001c3af033b51a6e2eeab6a5809e86
Author: Han-Wen Nienhuys <address@hidden>
Date:   Wed Oct 9 14:04:47 1996 +0200

    release: 0.0.1

commit 727cdcbadf23c1986b0aed547aa645c9813f351b
Author: Han-Wen Nienhuys <address@hidden>
Date:   Tue Oct 22 22:09:43 1996 +0200

    release: 0.0.2

which strongly suggests that origin and the given commit do not have a
common history in the repository.  So why is
a281aedda8d5ea550f8b851822315cf154acee52 still in there?

If I do git log --reverse a281aedda8d5 I get
commit 0ff96d5d41379dbb968507fd848642da518dc50b
Author: fred <fred>
Date:   Tue Jul 18 00:23:16 1995 +0000

    lilypond-1.0.1

commit 93d1d90d4645fc0f64ae310e0df224f00228ee78
Author: fred <fred>
Date:   Thu Sep 21 11:20:44 1995 +0000

    lilypond-1.0.1

as the purported starting point of the respective history.  Usually that
kind of history would have fallen by the wayside during garbage
collection.

It turns out that
git log --remotes --reverse

starts with
commit 4f4ad24a3bfeb77cfd0ecca104319607bfd28a63
Author: Han-Wen Nienhuys <address@hidden>
Date:   Wed Oct 9 14:04:46 1996 +0100

    Initial.

while
git log --all --reverse

starts with
commit 0ff96d5d41379dbb968507fd848642da518dc50b
Author: fred <fred>
Date:   Tue Jul 18 00:23:16 1995 +0000

    lilypond-1.0.1

here.  So apparently I have _local_ references that keep the old history
alive.

If I do
git log --all --reverse --source

then my history starts with
commit 0ff96d5d41379dbb968507fd848642da518dc50b refs/tags/release/1.7.25
Author: fred <fred>
Date:   Tue Jul 18 00:23:16 1995 +0000

    lilypond-1.0.1

So it is tags which keep the old history from getting garbage collected.

git tag -n 1000 | less

shows up quite a few strange tag annotations.  Huh.

-- 
David Kastrup