When using common deps include only specified packages, not all set

pkgs/tools/misc/gawp/default.nix

@@ -1,8 +1,31 @@
 # This file was generated by go2nix.
 { stdenv, lib, goPackages, fetchgit, fetchhg, fetchbzr, fetchsvn }:
 
+with builtins;
 with goPackages;
 
+let
+  depToSrc = jsonDep:
+    {
+      inherit (jsonDep) goPackagePath;
+      src = if jsonDep.fetch.type == "git" then
+        fetchgit {
+          inherit (jsonDep.fetch) url rev sha256;
+        }
+        else {};
+    };
+
+  importGodeps = { depsFile, filterPackages ? [] }:
+  let
+    deps = lib.importJSON depsFile;
+    external = filter (d: d ? include) deps;
+    direct = filter (d: d ? goPackagePath && (length filterPackages == 0 || elem d.goPackagePath filterPackages)) deps;
+  in
+    concatLists (map importGodeps (map (d: { depsFile = ./. + d.include; filterPackages = d.packages; }) external)) ++ (map depToSrc direct);
+
+  godeps = importGodeps { depsFile = ./deps.json; };
+in
+
 buildGoPackage rec {
   name = "gawp-${version}";
   version = "20160121-${stdenv.lib.strings.substring 0 7 rev}";
@@ -16,14 +39,5 @@ buildGoPackage rec {
     sha256 = "0r4bp4w3s9rkmg3cz9jb7d6ngh7vfj31p9kbim6mhilxvmgjk4ly";
   };
 
-  extraSrcs = map ( jsonDep:
-    {
-      inherit (jsonDep) goPackagePath;
-      src = if jsonDep.fetch.type == "git" then
-        fetchgit {
-          inherit (jsonDep.fetch) url rev sha256;
-        }
-        else {};
-    }
-  ) (builtins.fromJSON (builtins.readFile ../../../development/go-modules/libs.json));
+  extraSrcs = godeps;
 }

pkgs/tools/misc/gawp/deps.json

@@ -0,0 +1,10 @@
+[
+    {
+        "include": "../../../../development/go-modules/libs.json",
+        "packages": [
+            "golang.org/x/sys",
+            "gopkg.in/yaml.v2",
+            "gopkg.in/fsnotify.v1"
+        ]
+    }
+]