packaging: Use a recent bower2nix to have fetch-bower

Recent versions of bower2nix provide "fetch-bower" as a separate command. This
command is needed for the backported bower related utilities.

pkgs/backport-16.03-build-bower-components.nix

@@ -1,60 +1,67 b''
 # Backported buildBowerComponents so that we can also use it with the version
 # 16.03 which is the current stable at the time of this writing.
 #
 # This file can be removed once building with 16.03 is not needed anymore.
 
 { pkgs }:
 
 { buildInputs ? [], generated, ... } @ attrs:
 
 let
+  bower2nix-src = pkgs.fetchzip {
+    url = "https://github.com/rvl/bower2nix/archive/v3.0.1.tar.gz";
+    sha256 = "1zbvz96k2j6g0r4lvm5cgh41a73k9dgayk7x63cmg538dzznxvyb";
+  };
+
+  bower2nix = import "${bower2nix-src}/default.nix" { inherit pkgs; };
+
   fetchbower = import ./backport-16.03-fetchbower.nix {
     inherit (pkgs) stdenv lib;
-    inherit (pkgs.nodePackages) bower2nix;
+    inherit bower2nix;
   };
 
   # Fetches the bower packages. `generated` should be the result of a
   # `bower2nix` command.
   bowerPackages = import generated {
     inherit (pkgs) buildEnv;
     inherit fetchbower;
   };
 
 in pkgs.stdenv.mkDerivation (
   attrs
   //
   {
     name = "bower_components-" + attrs.name;
 
     inherit bowerPackages;
 
     builder = builtins.toFile "builder.sh" ''
       source $stdenv/setup
 
       # The project's bower.json is required
       cp $src/bower.json .
 
       # Dereference symlinks -- bower doesn't like them
       cp  --recursive --reflink=auto       \
           --dereference --no-preserve=mode \
           $bowerPackages bc
 
       # Bower install in offline mode -- links together the fetched
       # bower packages.
       HOME=$PWD bower \
           --config.storage.packages=bc/packages \
           --config.storage.registry=bc/registry \
           --offline install
 
       # Sets up a single bower_components directory within
       # the output derivation.
       mkdir -p $out
       mv bower_components $out
     '';
 
     buildInputs = buildInputs ++ [
       pkgs.git
       pkgs.nodePackages.bower
     ];
   }
 )