OpenVPN: don't fail to restart stopped units (#345993)

    openvpn-restart = {

      wantedBy = [ "sleep.target" ];

      path = [ pkgs.procps ];

      script = "pkill --signal SIGHUP --exact openvpn";

      #SIGHUP makes openvpn process to self-exit and then it got restarted by systemd because of Restart=always

      script = let

        unitNames = map (n: "openvpn-${n}.service") (builtins.attrNames cfg.servers);

      in "systemctl try-restart ${lib.escapeShellArgs unitNames}";

      description = "Sends a signal to OpenVPN process to trigger a restart after return from sleep";

    };

  };