bug#68359: Can't pull my channel because of, getaddrinfo -8 error

[Christina O'Donnell <cdo@mutix.org>]

Hi Simon, Paul,

I've also run into this bug and I believe it is due to the error being 
cached. This is clearly undesirable so this issue should stay open until 
that is resolved.

My reasoning for thinking it is a cache issues is:
  - An issue with package transformations should never cause an 
getaddrinfo error as Guix generally only goes up to servers for channels 
and build packages.
  - I ran into this after my gitlab instance had some outage, and 
persisted since my server came back up.
  - Pulling from a duplicate ref with the same hash succeeds, indicating 
that the bug occurs before the checkout is fetched.

I'm happy to have a stab at working on this. Currently working on 
reproducing this, it's not as simple as making the channel url point at 
a closed port (eg. https://localhost:1212). I even tried binding a SCTP 
server to the port, but I just get connection refused. Anyone have any 
ideas about this?

Should the title be changed to something like "Guix can cache 
getaddrinfo failures on `guix pull`"? (.. on the assumption that I'm 
proven right ;-)

I'll assign this to myself, if there are no objections.

Kind regards,

Christina