Dont build nerdfonts from source

pkgs/bck-nerdfont.nix

@@ -1,14 +1,14 @@
-{ stdenv
-, lib
-, dejavu_fonts
-, fetchFromGitHub
+{ nerdfonts
 , python3
+, runCommand
 , writeScript
 }:
 
 let
   py = python3.withPackages (p: [ p.fontforge ]);
 
+  src = nerdfonts.override { fonts = [ "DejaVuSansMono" ]; };
+
   # Stick a rectangle on the left edge of the
   # powerline symbol to avoid anti-aliasing artifacts
   postprocess = writeScript "postprocess.py" ''
@@ -18,40 +18,17 @@ let
     glyph = f[0xE0B0]
     bb = glyph.boundingBox()
     pen = glyph.glyphPen(replace=False)
-    pen.moveTo(bb[0],bb[1])
-    pen.lineTo(bb[0],bb[3])
-    pen.lineTo(bb[0]-150,bb[3])
-    pen.lineTo(bb[0]-150,bb[1])
+    pen.moveTo(0, bb[1])
+    pen.lineTo(0, bb[3])
+    pen.lineTo(-150, bb[3])
+    pen.lineTo(-150, bb[1])
     pen.closePath()
     os.unlink(sys.argv[1])
     f.generate(sys.argv[1])
   '';
 
 in
-stdenv.mkDerivation {
-  name = "bck-nerdfont";
-
-  dontUnpack = true;
-
-  src = fetchFromGitHub {
-    owner = "ryanoasis";
-    repo = "nerd-fonts";
-    rev = "v2.1.0";
-    sha256 = "j0cLZHOLyoItdvLOQVQVurY3ARtndv0FZTynaYJPR9E=";
-  };
-
-  buildPhase = ''
-    # Either Octicons or FontAwesome are required. Take your pick.
-    # They cause the fontlinux characters to move to the correct slots.
-    # (see fontlinuxExactEncodingPosition)
-    find ${dejavu_fonts}/share/fonts/truetype -name 'DejaVuSansMono*' -print0 |
-      xargs -0n1 ${py}/bin/python $src/font-patcher \
-        --fontlinux --octicons --powerline \
-        --postprocess ${postprocess}
-  '';
-
-  installPhase = ''
-    mkdir -p $out/share/fonts/truetype
-    cp -v *.ttf $out/share/fonts/truetype/
-  '';
-}
+runCommand "bck-nerdfont" { inherit src; } ''
+  find $src -name '*Complete.ttf' -exec install -D -t $out/share/fonts/truetype {} \;
+  find $out -name '*Complete.ttf' -exec ${postprocess} {} \;
+''