Impacted versions:
* 11.0

Steps to reproduce:
* Create company A
* Create company B
* Admin user with both companies but currently in company B
* Create Demo user only with company B
* Create fiscal position A to company A
* Create fiscal position B to company B
* Create vendor with fiscal position A with company A and the same vendor with fiscal position B in company B
* Create product and add the vendor created before
* Set like **Create a draft purchase order**
* Logging with Demo user
* Create sale order with one sale order line with route **make to order**
* Validate sale order

Current behavior:
The purchase order created by sale order has the fiscal position **company A**

Expected behavior:
The purchase order must have fiscal position **company B**
suppliers = procurement.product_id.seller_ids\
                .filtered(lambda r: (not r.company_id or r.company_id == procurement.company_id) and (not r.product_id or r.product_id == procurement.product_id))
            if not suppliers:
                procurement.message_post(body=_('No vendor associated to product %s. Please set one to fix this procurement.') % (procurement.product_id.name))
                continue
            supplier = procurement._make_po_select_supplier(suppliers)
            partner = supplier.name
            domain = procurement._make_po_get_domain(partner)
            if domain in cache:
                po = cache[domain]
            else:
                po = self.env['purchase.order'].search([dom for dom in domain])
                po = po[0] if po else False
                cache[domain] = po
            if not po:
                vals = procurement._prepare_purchase_order(partner)
                po = self.env['purchase.order'].create(vals)
                name = (procurement.group_id and (procurement.group_id.name + ":") or "") + (procurement.name != "/" and procurement.name or procurement.move_dest_id.raw_material_production_id and procurement.move_dest_id.raw_material_production_id.name or "")
                message = _("This purchase order has been created from: <a href=# data-oe-model=procurement.order data-oe-id=%d>%s</a>") % (procurement.id, name)
                po.message_post(body=message)
                cache[domain] = po
            elif not po.origin or procurement.origin not in po.origin.split(', '):
                
                if po.origin:
                    if procurement.origin:
                        po.write({'origin': po.origin + ', ' + procurement.origin})
                    else:
                        po.write({'origin': po.origin})
                else:
                    po.write({'origin': procurement.origin})