Re: use of git-fetch

[Federico Beffa <beffa@ieee.org>]

On Fri, Jul 24, 2015 at 12:50 AM, Ludovic Courtès <ludo@gnu.org> wrote:
> Federico Beffa <beffa@ieee.org> skribis:
>
>> On Wed, Jul 22, 2015 at 11:10 PM, Ludovic Courtès <ludo@gnu.org> wrote:
>>> Federico Beffa <beffa@ieee.org> skribis:
>>>
>>>>               (sha256
>>>>                (base32
>>>>                 "06mc7kh3fzdh2mqkyynjnp0xpv30yfaiik8bqv8z5b6hldji3cky"))))
>>>
>>> [...]
>>>
>>>>               (sha256
>>>>                (base32
>>>>                 "06mc7kh3fzdh2mqkyynjnp0xpv30yfaiik8bqv8z5b6hldji3cky"))))
>>>
>>> Both recipes are telling that they use the same source.  So the daemon
>>> cleverly saves one download since it already has the thing with that
>>> hash on disk.  See?  :-)
>>
>> Thanks for the reply!
>>
>> I thought about this and, before posting, I also tried with an hash
>> where the first character was changed from '0' to '6'. It gave the
>> same result, even after deleting any existing 'emacs-dash' and
>> 'emacs-s' derivation in the store. In my understanding that shouldn't
>> happen. Is that correct?
>
> Right, but we’d have to check the exact sequence of actions that you
> took.

Basically I did:

1. write the package for emacs-dash
2. guix build emacs-dash
3. copy emacs-dash and make emacs-s out of it, keeping the hash unchanged
4. guix build emacs-s

Boom: in the generated derivation I find dash.el instead of s.el.

5. change the first char of the hash 0->6

Boom: same.

6. change the full hash to a sequence of 6s.

OK, now I get the expected result.

7. change hash, rebuild and inspect.

Regards,
Fede