Sadly, we can't instruct systemd to properly restart device-name.swap when this service restarts (or I haven't found the way to do so). As of now blindly restarting it would only get you a bunch of errors about device already used -- let's avoid it.
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.
