anchor.diff:  
     patches = nixPatches ++ packageUpgradePatches ++ [
       ./patches/known-padics-bug.patch
  +
  +    # /home/timo/tmp/0003-Revert-Something-related-to-the-sphinxbuild-seems-to.patch
     ];
   
     postPatch = ''
  
positive.code:     # https://trac.sagemath.org/ticket/25260
      ./patches/numpy-1.14.3.patch
  
      # https://trac.sagemath.org/ticket/25862
      ./patches/eclib-regulator-precision.patch
      ./patches/eclib-20180710.patch
  
      # https://trac.sagemath.org/ticket/25567
      (fetchpatch {
        name = "pari-2.11.0.patch";
        url = "https://git.sagemath.org/sage.git/patch/?id=7af4748cab37d651eaa88be501db88f4a5ffc584";
        sha256 = "13f740ly3c19gcmhjngiycvmc3mcfj61y00i6jv0wmfgpm2z3ank";
      })
  
      # ntl upgrade
      (fetchpatch {
        name = "lcalc-c++11.patch";
  
negative.code: , fetchpatch
  }:
  stdenv.mkDerivation rec {
    version = "8.4.beta3";
    name = "sage-src-${version}";
  
    src = fetchFromGitHub {
      owner = "sagemath";
      repo = "sage";
      rev = version;
      sha256 = "14i2a2dzgcl9wj0067kxy5k1aq4g5yp1mhckghz0qm48ygvp1a4j";
    };
  
    nixPatches = [
  