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**
if self.picking_type_id.default_location_dest_id.usage != 'customer':
            self.dest_address_id = False
    @api.multi
    def action_rfq_send(self):
        '''
        This function opens a window to compose an email, with the edi purchase template message loaded by default
        '''
        self.ensure_one()
        ir_model_data = self.env['ir.model.data']
        try:
            if self.env.context.get('send_rfq', False):
                template_id = ir_model_data.get_object_reference('purchase', 'email_template_edi_purchase')[1]
            else:
                template_id = ir_model_data.get_object_reference('purchase', 'email_template_edi_purchase_done')[1]
        except ValueError:
            template_id = False
        try:
            compose_form_id = ir_model_data.get_object_reference('mail', 'email_compose_message_wizard_form')[1]
        except ValueError:
            compose_form_id = False
        ctx = dict(self.env.context or {})
        ctx.update({