bug#47266: guix pull: error (substituter)

[Brian Zwahr]

I was pointed to this issue from the IRC channel. I am also 
experiencing similar "bad response" errors during `guix pull` and `guix 
upgrade`. Thanks to help from IRC, I was able to sort of work around 
the issue by simply brute-forcing the commands, running them over and 
over again until they completed successfully.

Here are all the `guix pull` attempts it took: 
<https://paste.debian.net/hidden/3dc48b23/>
Here are the all the `guix upgrade` attempts after the pull finally 
completed: <https://paste.debian.net/hidden/e453dd85/>