Success sbatch launch in MN4 with nbody seq

bsc/garlic/nbody/default.nix

@@ -29,12 +29,25 @@ stdenv.mkDerivation {
     "BS=${toString blocksize}"
   ];
 
+  dontPatchShebangs = true;
+
   installPhase = ''
     mkdir -p $out/bin
     cp nbody $out/bin/
 
     cat > $out/bin/run <<EOF
-    #!/bin/bash
+    #!/bin/sh
+
+    # We need to enter the nix namespace first, in order to have /nix
+    # available, so we use this hack:
+    if [ ! -e /nix ]; then
+      echo "running nix-setup \$0"
+      exec nix-setup \$0
+    fi
+
+    ls -l /nix
+    pwd
+
     exec $out/bin/nbody -p ${toString particles} -t ${toString timesteps}
     EOF