Bjørn Forsman 9050077cff switch-to-configuration: use absolute path to systemd-escape
Fixes issue when upgrading from very old NixOS systems that don't have
systemd-escape in $PATH:

  $ sudo nixos-rebuild switch
  ...
  building the system configuration...
  updating GRUB 2 menu...
  Can't exec "systemd-escape": No such file or directory at /nix/var/nix/profiles/system/bin/switch-to-configuration line 264.
  Unable to escape /!
2016-07-01 08:35:38 +02:00
..
2016-04-18 21:13:18 +02:00

*** 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.