Impacted versions: all

On the model "ir.model.field" there is a field called "copy" : https://github.com/odoo/odoo/blob/master/odoo/addons/base/models/ir_model.py#L322

This name conflict with the method "copy" that exist browse record
https://github.com/odoo/odoo/blob/master/odoo/models.py#L4203

This make impossible to use the method copy on ir.model.field
And also raise warning when we make an inherits of the class ir.model.field (https://github.com/odoo/odoo/blob/master/odoo/models.py) as the field conflict with the method name

@odony @rco-odoo 

odoo/addons/test_new_api/tests/test_schema.py
'table_schema': u'public',
                'udt_catalog': self.cr.dbname,
                'udt_name': u'int4',
                'udt_schema': u'pg_catalog',
            },
            field.column2: {
                'character_maximum_length': None,
                'column_default': None,
                'column_name': u'category',
                'data_type': u'integer',
                'datetime_precision': None,
                'is_nullable': u'NO',
                'is_updatable': u'YES',
                'numeric_precision': 32,
                'numeric_precision_radix': 2,
                'numeric_scale': 0,
                'table_catalog': self.cr.dbname,
                'table_name': u'test_new_api_discussion_category',
                'table_schema': u'public',
                'udt_catalog': self.cr.dbname,
                'udt_name': u'int4',
                'udt_schema': u'pg_catalog'
            },
        })
        foreign_keys = self.get_foreign_keys(field.relation)
        self.assertItemsEqual(foreign_keys, [
            (field.relation, field.column1, model._table, 'id', 'CASCADE'),
            (field.relation, field.column2, comodel._table, 'id', 'CASCADE'),
        ])