gist: fix evaluation

pkgs/tools/text/gist/Gemfile

@@ -0,0 +1,2 @@
+source "https://rubygems.org"
+gem "gist"

pkgs/tools/text/gist/Gemfile.lock

@@ -0,0 +1,10 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    gist (4.3.0)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  gist

pkgs/tools/text/gist/default.nix

@@ -1,32 +1,15 @@
-{ stdenv
-, fetchurl
-, makeWrapper
-, ruby
-, rake
-}:
+{ stdenv, lib, bundlerEnv }:
 
-let version = "v4.3.0";
-in stdenv.mkDerivation rec {
+let version = "4.3.0";
+in bundlerEnv {
   name = "gist-${version}";
-
-  src = fetchurl {
-    url = "https://github.com/defunkt/gist/archive/${version}.tar.gz";
-    sha256 = "92b91ffe07cc51ca8576b091e7123b851ee0d7d2d3f0e21d18b19d8bd8f9aa47";
-  };
-
-  buildInputs = [ rake makeWrapper ];
-
-  installPhase = ''
-    rake install prefix=$out
-
-    wrapProgram $out/bin/gist \
-      --prefix PATH : ${ruby}/bin \
-  '';
-
-  meta = {
+  gemfile = ./Gemfile;
+  lockfile = ./Gemfile.lock;
+  gemset = ./gemset.nix;
+  meta = with lib; {
     homepage = "http://defunkt.io/gist/";
     description = "upload code to https://gist.github.com (or github enterprise)";
-    platforms = stdenv.lib.platforms.all;
-    license = stdenv.lib.licenses.mit;
+    platforms = platforms.all;
+    license = licenses.mit;
   };
 }

pkgs/tools/text/gist/gemset.nix

@@ -0,0 +1,9 @@
+{
+  "gist" = {
+    version = "4.3.0";
+    source = {
+      type = "gem";
+      sha256 = "0az6l8nq433sszailr7kglh21l3gkcb11k7ag6668nyxxplm9rp0";
+    };
+  };
+}

pkgs/top-level/all-packages.nix

@@ -727,8 +727,7 @@ let
 
   fop = callPackage ../tools/typesetting/fop { };
 
-  # Evaluation broken by recent ruby changes.
-  # gist = callPackage ../tools/text/gist { };
+  gist = callPackage ../tools/text/gist { };
 
   mcrl = callPackage ../tools/misc/mcrl { };