Merge pull request #210505 from notgne2/fix/systemd-initrd-allow-symlink

nixos/systemd-initrd: allow symlink into when checking for `/prepare-root`

nixos/modules/system/boot/systemd/initrd.nix

···
 
           # If we are not booting a NixOS closure (e.g. init=/bin/sh),
           # we don't know what root to prepare so we don't do anything
-          if ! [ -x "/sysroot$closure/prepare-root" ]; then
+          if ! [ -x "/sysroot$(readlink "/sysroot$closure/prepare-root" || echo "$closure/prepare-root")" ]; then
             echo "NEW_INIT=''${initParam[1]}" > /etc/switch-root.conf
             echo "$closure does not look like a NixOS installation - not activating"
             exit 0