anchor.diff: -{ buildPythonPackage, lib, fetchFromGitHub, nixosTests
  +{ buildPythonPackage, lib, fetchFromGitHub, isPy27, nixosTests
   , alembic
   , aniso8601
   , Babel
  
positive.code: , jinja2
  , Mako
  , markupsafe
  , python-dateutil
  , pytz
  , six
  
negative.code: 
    checkInputs = [
      flask_testing
    ] ++ lib.optionals isPy27 [ mock ];
  
    passthru.tests = {
      inherit (nixosTests) ihatemoney;
  