[bug#47160] [PATCH] scripts: substitute: Add back some error handling.

["Ludovic Courtès" <ludo@gnu.org>]

Howdy!

Christopher Baines <mail@cbaines.net> skribis:

> In f50f5751fff4cfc6d5abba9681054569694b7a5c, the way fetch was called within
> process-substitution was changed.  As call-with-cached-connection actually
> includes important error handling for the opening of a HTTP request, this
> change removed some error handling.  This commit adds that back.
>
> Fixes <https://bugs.gnu.org/47157>.
>
> * guix/scripts/substitute.scm (call-with-cached-connection): New procedure.
> (with-cached-connection): New syntax rule.
> (process-substitution): Retry once for some errors when making HTTP requests
> to fetch substitutes.

[...]

> The call-with-connection-error-handling was added in
> 20c08a8a45d0f137ead7c05e720456b2aea44402, but that error handling was
> previously inside of open-connection-for-uri/maybe, which is related
> to (call-)with-cached-connection which was used in process-substitution, but
> only actually used with call-with-cached-connection when used in
> fetch-narinfos.
>
> There's some handling for similar errors within with-networking, which is used
> within process-substitution.
>
> * guix/scripts/substitute.scm (process-substitution): Remove
> call-with-connection-error-handling call.

Both LGTM, thank you!

Ludo’.