Comment 31 for bug 1871268

I'm running into this building a Docker image that's "FROM ubuntu:20.04" and just trying to install libc6:i386. Here's the simplest reproducer I've come up with:

```
$ docker pull ubuntu:20.04
20.04: Pulling from library/ubuntu
Digest: sha256:cbcf86d7781dbb3a6aa2bcea25403f6b0b443e20b9959165cf52d2cc9608e4b9
Status: Image is up to date for ubuntu:20.04
docker.io/library/ubuntu:20.04

$ docker run --rm ubuntu:20.04 sh -c 'dpkg --add-architecture i386 && apt-get update -qq && apt-get install -y libc6:i386'
Reading package lists...
Building dependency tree...
Reading state information...
The following additional packages will be installed:
  gcc-10-base:i386 libc6 libcrypt1:i386 libgcc-s1:i386 libidn2-0:i386
  libunistring2:i386
Suggested packages:
  glibc-doc locales glibc-doc:i386 locales:i386
The following NEW packages will be installed:
  gcc-10-base:i386 libc6:i386 libcrypt1:i386 libgcc-s1:i386 libidn2-0:i386
  libunistring2:i386
The following packages will be upgraded:
  libc6
1 upgraded, 6 newly installed, 0 to remove and 1 not upgraded.
Need to get 5871 kB of archives.
After this operation, 15.2 MB of additional disk space will be used.
...
Processing triggers for libc-bin (2.31-0ubuntu9) ...
E: Could not configure 'libc6:i386'.
E: Could not perform immediate configuration on 'libgcc-s1:i386'. Please see man 5 apt.conf under APT::Immediate-Configure for details. (2)
```

Looking at my GitHub Actions logs, it was working fine two days ago (Sep 21) and was broken starting yesterday (Sep 22), in case that helps narrow down which uploads might have caused the breakage.