printer-driver-postscript-hp Depends: hplip
hplip Depends: policykit-1
policykit-1 Depends: libpam-systemd
libpam-systemd Depends: systemd (= 204-14)

Since the last in the above is a versioned dependency, that means you can't use systemd-shim to satisfy this dependency.

I do think we should migrate to systemd. However, it's unfortunate that this change is being rushed like this. I want to migrate my personal laptop to systemd—but not before I have the time to deal with any fallout that might result, and to make sure I can properly migrate my configuration.

Workaround (for now): hold policykit-1 at 0.105-3 rather than have it upgrade to 0.105-6. That version doesn't have a dependency on libpam-systemd.

Off-hand questions:

  • Why does one need to log in to an init system? (yes, yes, it's probably a session PAM module, not an auth or password module. Still)
  • What does policykit do that can't be solved with proper use of Unix domain sockets and plain old unix groups?

All this feels like another case of overengineering, like most of the *Kit thingies.

Update: so the systemd package doesn't actually cause systemd to be run, there are other packages that do that, and systemd-shim can be installed. I misread things. Of course, the package name is somewhat confusing... but that's no excuse.