KDM and LightDM (at least with autologin) call the xsession-script with two arguments: the first is the path of the xsession script itself, while the second one are the actual arguments. The line to re-exec the script under systemd-cat only forwarded a single argument, therefore breaking LightDM and KDM login. This commit fixes the issue by always forwarding all the arguments.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.