This means following the plan [3] for:
- [x] jenkins-debian1: the debian package build node [1]
- [ ] thyssen: jenkins server node [2]
It should be fine to just upgrade the nodes as their respective major tooling are part of debian packages.
[1] The main tools here are sbuild and chroot.
[2] The main tooling are within docker constraint (so it's "pinned")
[3]
```
task=T3770
puppet agent --disable "$task: dist-upgrade to bullseye"
cd /etc
sed -i -e 's/buster/bullseye/' /etc/apt/sources.list.d/*
sed -i -e 's,bullseye/updates,bullseye-security,' /etc/apt/sources.list.d/debian-security.list
git status
grep bullseye-security /etc/apt/sources.list.d/debian-security.list
git add .
git commit -m "$task: Migrate sources.list to bullseye"
apt update
apt upgrade -y
apt dist-upgrade -y
reboot
puppet agent --enable && puppet agent --test
```