buildPython*: bring back buildPython*.override (#366593)

        }

      else

        result

    );

    )

    // lib.optionalAttrs (f ? override) {

      # Support overriding `f` itself, e.g. `buildPythonPackage.override { }`.

      # Ensure `makeOverridablePythonPackage` is applied to the result.

      override = lib.mirrorFunctionArgs f.override (fdrv: makeOverridablePythonPackage (f.override fdrv));

    };

  mkPythonDerivation =

    if python.isPy3k then ./mk-python-derivation.nix else ./python2/mk-python-derivation.nix;