Make install-grub.pl work when $PATH is empty

modules/system/boot/loader/grub/grub.nix

@@ -18,6 +18,7 @@ let
         version extraConfig extraPerEntryConfig extraEntries
         extraEntriesBeforeNixOS configurationLimit copyKernels timeout
         default devices;
+      path = makeSearchPath "bin" [ pkgs.coreutils pkgs.gnused pkgs.findutils pkgs.gnugrep ];
     });
 
 in

modules/system/boot/loader/grub/install-grub.pl

@@ -38,6 +38,7 @@ my $configurationLimit = int(get("configurationLimit"));
 my $copyKernels = get("copyKernels") eq "true";
 my $timeout = int(get("timeout"));
 my $defaultEntry = int(get("default"));
+$ENV{'PATH'} = get("path");
 
 die "unsupported GRUB version\n" if $grubVersion != 1 && $grubVersion != 2;