anchor.diff: -{ lib, buildPythonPackage, fetchFromGitHub, isPy27, pythonOlder
  +{ lib, buildPythonPackage, fetchFromGitHub, isPy27, pythonOlder, fetchpatch
   , cachecontrol
   , cachy
   , cleo
  
positive.code:     "prereleases_if_they_are_compatible"
      # requires git history to work correctly
      "default_with_excluded_data"
    ];
  
    meta = with lib; {
  
negative.code:      --replace "requests-toolbelt = \"^0.8.0\"" "requests-toolbelt = \"^0.9.1\"" \
       --replace 'importlib-metadata = {version = "~1.1.3", python = "<3.8"}' \
         'importlib-metadata = {version = ">=1.3,<2", python = "<3.8"}' \
       --replace "tomlkit = \"^0.5.11\"" "tomlkit = \"<2\"" \
       --replace "cleo = \"^0.7.6\"" "cleo = \"^0.8.0\"" \
       --replace "version = \"^20.0.1\", python = \"^3.5\"" "version = \"^21.0.0\", python = \"^3.5\"" \
       --replace "clikit = \"^0.4.2\"" "clikit = \"^0.6.2\""
  