[FIX] payment: render acquirer form values even if partner is missing
[FIX] payment: render acquirer form values even if partner is missing

When no `partner_id` was passed to `render()` and the acquirer
had a fees computation method, (e.g. Paypal), it would crash.
Could happen when coming through the /website_payment/pay
controller, for instance.

dfang/odoo,hip-odoo/odoo,storm-computers/odoo,microcom/odoo,microcom/odoo,Elico-Corp/odoo_OCB,ygol/odoo,dfang/odoo,Elico-Corp/odoo_OCB,microcom/odoo,dfang/odoo,ygol/odoo,ygol/odoo,laslabs/odoo,bplancher/odoo,ygol/odoo,laslabs/odoo,laslabs/odoo,bplancher/odoo,hip-odoo/odoo,hip-odoo/odoo,storm-computers/odoo,storm-computers/odoo,dfang/odoo,hip-odoo/odoo,ygol/odoo,Elico-Corp/odoo_OCB,bplancher/odoo,microcom/odoo,bplancher/odoo,laslabs/odoo,Elico-Corp/odoo_OCB,storm-computers/odoo,microcom/odoo,laslabs/odoo,microcom/odoo,ygol/odoo,dfang/odoo,hip-odoo/odoo,storm-computers/odoo,hip-odoo/odoo,laslabs/odoo,storm-computers/odoo,bplancher/odoo,dfang/odoo,ygol/odoo,Elico-Corp/odoo_OCB,bplancher/odoo,Elico-Corp/odoo_OCB