Package APT provider specify target-release
How do I achieve in PP a
apt-get install -t jessie-backports systemd
Only systemd and its dependencies shall come from
jessie-backports. Everything else still comes from stable.
No, I definitely won't specify a version number in
apt-get install systemd/jessie-backports is not a solution. It'll remove
linux-image and dozens of applications packages (like xserver).
I looked, whether a
apt::pin would help, but there you'd have to specify all packages by name, which I won't. As far as I've looked you can't specify a pin, „package systemd and all its dependencies“.
PS: Yes, I know mixing testing, backports, and stable all together can lead to problems. Yes, I know