Follow up of be06eb47bdf8b5f2cc281e3986818faf59e3a616 . Even if postgresql < 10.0 is not officially
supported this fix allows to keep compatibility with older postgresql.
closesodoo/odoo#46243
X-original-commit: 7e218be37cf0bc2c2c4fd4284b93ba99de679692
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>