Add a utility function "fetchGitHub"

This is a small wrapper around fetchzip. It allows you to say:

  src = fetchGitHub {
    owner = "NixOS";
    repo = "nix";
    rev = "924e19341a5ee488634bc9ce1ea9758ac496afc3"; # or a tag
    sha256 = "1ld1jc26wy0smkg63chvdzsppfw6zy1ykf3mmc50hkx397wcbl09";
  };

pkgs/tools/networking/dd-agent/default.nix

@@ -1,12 +1,14 @@
-{ stdenv, fetchzip, python, pythonPackages, sysstat, unzip, tornado
+{ stdenv, fetchGitHub, python, pythonPackages, sysstat, unzip, tornado
 , makeWrapper }:
 
 stdenv.mkDerivation rec {
   version = "4.2.1";
   name = "dd-agent-${version}";
 
-  src = fetchzip {
-    url = "https://github.com/DataDog/dd-agent/archive/${version}.zip";
+  src = fetchGitHub {
+    owner = "DataDog";
+    repo = "dd-agent";
+    rev = version;
     sha256 = "06f9nkvnpfzs2nw75cac2y9wnp2bay4sg94zz0wjm8886rigjjjm";
   };
 

pkgs/tools/text/recode/default.nix

@@ -1,14 +1,15 @@
 # XXX: this may need -liconv on non-glibc systems.. 
 
-{ stdenv, fetchgit, python, perl, autoconf, automake, libtool, intltool, flex }:
+{ stdenv, fetchGitHub, python, perl, autoconf, automake, libtool, intltool, flex }:
 
 stdenv.mkDerivation rec {
-  name = "recode-3.7-pff85fdbd";
+  name = "recode-3.7-2fd838565";
 
-  src = fetchgit {
-    url = https://github.com/pinard/Recode.git;
+  src = fetchGitHub {
+    owner = "pinard";
+    repo = "Recode";
     rev = "2fd8385658e5a08700e3b916053f6680ff85fdbd";
-    sha256 = "1xhlfmqld6af16l444jli9crj9brym2jihg1n6lkxh2gar68f5l7";
+    sha256 = "06vyjqaraamcc5vka66mlvxj27ihccqc74aymv2wn8nphr2rhh03";
   };
 
   buildInputs = [ python perl autoconf automake libtool intltool flex ];

pkgs/top-level/all-packages.nix

@@ -340,6 +340,11 @@ let
 
   fetchzip = import ../build-support/fetchzip { inherit lib fetchurl unzip; };
 
+  fetchGitHub = { owner, repo, rev, sha256 }: fetchzip {
+    url = "https://github.com/${owner}/${repo}/archive/${rev}.zip";
+    inherit sha256;
+  };
+
   resolveMirrorURLs = {url}: fetchurl {
     showURLs = true;
     inherit url;