Adding an option to include build dependencies into ISO image

svn path=/nixos/trunk/; revision=23502

modules/installer/cd-dvd/iso-image.nix

@@ -54,6 +54,18 @@ let
       '';
     };
 
+    isoImage.includeSystemBuildDependencies = mkOption {
+      default = false;
+      example = true;
+      description = ''
+        Set this option to include all the needed sources etc in the
+        image. It significantly increases image size. Use that when
+        you want to be able to keep all the sources needed to build your
+        system or when you are going to install the system on a computer
+        with slow on non-existent network connection.
+      '';
+    };
+
   };
 
 
@@ -164,7 +176,9 @@ in
   isoImage.storeContents =
     [ config.system.build.bootStage2
       config.system.build.toplevel
-    ];
+    ] ++ 
+    (optional config.isoImage.includeSystemBuildDependencies
+      config.system.build.toplevel.drvPath);
 
   # Create the squashfs image that contains the Nix store.
   system.build.squashfsStore = import ../../../lib/make-squashfs.nix {