Re: On raw strings in <origin> commit field

["Ludovic Courtès" <ludo@gnu.org>]

Hello!

Timothy Sample <samplet@ngyro.com> skribis:

> If you want a concrete example to think through, there’s ‘eclib’.  Our
> package says it’s version “20190909”, but that’s not what upstream calls
> version “20190909”.  It looks like when we packaged ‘eclib’, that tag
> pointed to commit 19e7e3e74268bf78bd9a1c4ba07597d5434fb166, but now it
> points to bfbbd7c414521e1bf5e718a2925ea8ad845a2e87.

[...]

> First, as expected, finding the original commit was painful.  SWH did
> not record the old version of the tag.

It probably did: SWH archives the “history of histories”.  However, our
SWH code, ‘lookup-origin-revision’, is looking at the tag found in the
latest snapshot, which is not helpful in this case.

[...]

> Second, these cases are very, very rare.  (I’ve essentially checked
> every Git origin since Guix version 1.0.0, and this problem is not one
> that worries me).  “Tricking Peer Review”-style problems seem to be much
> more prevalent.  When tracking down a “difficult” Git origin, the first
> thing I do is grep the Guix Git history for a “oops I committed the
> wrong hash” message.  I recommend we focus our energies there before
> worrying too much about replacing tags with commits or using both or
> whatever.

Agreed, it’d be nice to address, but not concern #1.

> And as a bonus, if you want to be really kind to future time travellers,
> when fixing an errant hash, please include a nice hint as to what the
> original hash was for (like a commit hash).  We have commit
> ca5a791f6285b08506ccd662d5911ccf0c4d1ece in our repo, which says:
>
>> The previous hash was from the "dev" branch of the repository.
>
> I can’t find the source for the previous hash, and if I could actually
> travel through time, I would change the commit message to:
>
>> The previous hash was from commit abcd0123..., which comes from the
>> "dev" branch of the repository.

In commit 944bd79113b9c856b11dd2b40d40e0274a9f4dd9 I added an
explanation right in the source; I think that’s a transparent and clear
way of handling issues with tags modified in place.

Ludo’.