data/fonts: simpler cleanups

pkgs/data/fonts/caladea/default.nix

@@ -1,22 +1,19 @@
-{stdenv, fetchurl}:
+{stdenv, fetchzip}:
 
-stdenv.mkDerivation rec {
-  name = "caladea-${version}";
+let
   version = "20130214";
+in fetchzip rec {
+  name = "caladea-${version}";
 
-  src = fetchurl {
-    url = "https://commondatastorage.googleapis.com/chromeos-localmirror/distfiles/crosextrafonts-${version}.tar.gz";
-    sha256 = "02addvvkbvf3bn21kfyj10j9w1c8hdxxld4wjmnc1j8ksqpir3f4";
-  };
-
-  phases = ["unpackPhase" "installPhase"];
-
-  installPhase = ''
+  url = "https://commondatastorage.googleapis.com/chromeos-localmirror/distfiles/crosextrafonts-${version}.tar.gz";
+  postFetch = ''
+    tar -xzvf $downloadedFile --strip-components=1
     mkdir -p $out/etc/fonts/conf.d
     mkdir -p $out/share/fonts/truetype
     cp -v *.ttf $out/share/fonts/truetype
     cp -v ${./cambria-alias.conf} $out/etc/fonts/conf.d/30-cambria.conf
   '';
+  sha256 = "0kwm42ggr8kvcn3554cpmv90xzam1sdncx7x3zs3bzp88mxrnv1z";
 
   meta = with stdenv.lib; {
     # This font doesn't appear to have any official web site but this