adds singularity debug test

pkgs/default.nix

@@ -54,7 +54,6 @@ let
     # library of nix expressions
     argolib       = import ../lib/utils.nix;
 
-    singularity = bleeding.singularity;
     # Argo components (source overridabel via argument)
     aml           = callPackage ./aml        {
       src=aml-src;
@@ -485,6 +484,19 @@ let
     });
 
     bld = bleeding;
+
+
+    singularityDebugTest = pkgs.stdenv.mkDerivation rec {
+      name = "singdebg";
+      src = ../dhrun ;
+      installPhase = ''
+        mkdir -p $out
+        singularity --version &> $out/version
+        singularity --help &> $out/version
+        '';
+      unpackPhase = "true";
+    };
+
   };
 
 # re-exporting a full nixpkgs-like package set