Fixed a regression in gis introduced by Query.select_fields removal

            self.query.add_select_related([field_name])

            compiler = self.query.get_compiler(self.db)

            compiler.pre_sql_setup()

            rel_table, rel_col = self.query.related_select_cols[self.query.related_select_fields.index(geo_field)]

            for (rel_table, rel_col), field in self.query.related_select_cols:

                if field == geo_field:

                    return compiler._field_column(geo_field, rel_table)

            raise ValueError("%r not in self.query.related_select_cols" % geo_field)

        elif not geo_field in opts.local_fields:

            # This geographic field is inherited from another model, so we have to

            # use the db table for the _parent_ model instead.