nix: don't allow overriding the import packages. This causes overlays to fail

default.nix

@@ -11,18 +11,19 b' args@'
 , ...
 }:
 
-let pkgs_ = (import <nixpkgs> {}); in
+let
+  pkgs_ = (import <nixpkgs> {});
+in
 
 let
-
-  pkgs = args.pkgs or (import <nixpkgs> {
+  pkgs = import <nixpkgs> {
     overlays = [
       (import ./pkgs/overlays.nix)
     ];
     inherit
       (pkgs_)
       system;
-  });
+  };
 
   # Works with the new python-packages, still can fallback to the old
   # variant.
@@ -39,7 +40,7 b' let'
     in
       !builtins.elem (basename path) [
         ".git" ".hg" "__pycache__" ".eggs" ".idea" ".dev"
-        "bower_components" "node_modules"
+        "node_modules" "node_binaries"
         "build" "data" "result" "tmp"] &&
       !builtins.elem ext ["egg-info" "pyc"] &&
       # TODO: johbo: This check is wrong, since "path" contains an absolute path,

release.nix

@@ -1,14 +1,12 b''
 # This file defines how to "build" for packaging.
 
-{ pkgs ? import <nixpkgs> {}
-, doCheck ? true
+{ doCheck ? true
 }:
 
 let
   vcsserver = import ./default.nix {
     inherit
-      doCheck
-      pkgs;
+      doCheck;
   };
 
 in {