bug#57559: guix pull fails on http status code 503

[zimoun]

Hi Maxime,

On Thu, 08 Sep 2022 at 02:55, Maxime Devos <maximedevos@telenet.be> wrote:

>> Well, %default-guix-channel is somehow a corner use-case when the
>> regular use-case seems about a failure of additional channels.
>
> The ‘Guix is unavailable’ was just a simple example. For the example, 
> you can replace it, with, say nonguix. Automatically removing the 
> additional channels upon 503 is undesirable I'd think, though the error 
> messages will be different.

My point is that ’Guix is unavailable’ is special and it appears to me
expected to raise an error.  Other said,

 1. if %default-guix-channel (or its mirrors) is unreachable,
    then stop the pull; as it is currently done.
 2. if an extra channel is unreachable,
    then keep the last local revision of this channel
    and try the others.

For sure, #2 can break the whole pull if something in the Guix channel
changed *and* the channel depends on this something.  But we cannot do
more than raise an error.


Cheers,
simon