Made GeoDjango GeometryField stop accepting a 'null' keyword argument as per...

from __future__ import unicode_literals

import warnings

from django import forms

from django.utils import six

from django.utils.translation import ugettext_lazy as _

        # defaults (e.g., allow None).

        self.srid = kwargs.pop('srid', None)

        self.geom_type = kwargs.pop('geom_type', self.geom_type)

        if 'null' in kwargs:

            kwargs.pop('null', True)

            warnings.warn("Passing 'null' keyword argument to GeometryField is deprecated.",

                DeprecationWarning, stacklevel=2)

        super(GeometryField, self).__init__(**kwargs)

        self.widget.attrs['geom_type'] = self.geom_type