[FIX] purchase: wrong condition in mail template
[FIX] purchase: wrong condition in mail template

Before checking the first element of
'partner_id.child_ids', rather check that
the partner and not the object has children,
to avoid crashes when the partner of the PO
is a company.
opw-1826359

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo