shell.nix: patch nixpkgs to add a tex pkg

shell.nix

@@ -1,12 +1,36 @@
 let 
-  pkgs = import ((import <nixpkgs> {}).pkgs.fetchFromGitHub {
+  nixpkgs = import <nixpkgs> {};
+  pkgsSrc = nixpkgs.pkgs.fetchFromGitHub {
     owner = "nixos";
     repo = "nixpkgs-channels";
     rev = "6715afca34f7ece882b82c2250a4f6dade42eac5"; # vimtex update
     sha256 = "1ix8k5sm01i75wxnfrlwbmc8xs8dn5zna7jb4v387h8zy8a74d8m";
-  }) {};
-in pkgs.stdenv.mkDerivation { 
+  };
+  pkgs = import (nixpkgs.stdenv.mkDerivation {
+    name = "patchedPackages";
+    src = pkgsSrc;
 
+    patches = [
+      (nixpkgs.fetchurl {
+        url="https://patch-diff.githubusercontent.com/raw/NixOS/nixpkgs/pull/15829.patch";
+        sha256 = "0a41nspiqs5i32pfzxqm8dp8qhfaajrw622lmlcvlvgbhpkac5r1";
+       })
+    ];
+
+    installPhase = ''
+      mkdir -p $out
+      cp -a * $out
+    '';
+
+    phases = ''
+      unpackPhase
+      patchPhase
+      installPhase
+    '';
+
+  }) {};
+
+in pkgs.stdenv.mkDerivation {
   name = "msc-thesis";
   buildInputs = [ 
     pkgs.pandoc