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**
addons/purchase/models/purchase.py
'product_uom_qty': min(procurement_qty, diff_quantity),
                    'move_dest_id': procurement.move_dest_id.id,  
                    'procurement_id': procurement.id,
                    'propagate': procurement.rule_id.propagate,
                })
                res.append(tmp)
                diff_quantity -= min(procurement_qty, diff_quantity)
        if float_compare(diff_quantity, 0.0,  precision_rounding=self.product_uom.rounding) > 0:
            template['product_uom_qty'] = diff_quantity
            res.append(template)
        return res
    @api.multi
    def _create_stock_moves(self, picking):
        moves = self.env['stock.move']
        done = self.env['stock.move'].browse()
        for line in self:
            for val in line._prepare_stock_moves(picking):
                done += moves.create(val)
        return done
    @api.multi
    def unlink(self):
        for line in self:
            if line.order_id.state in ['purchase', 'done']:
                raise UserError(_('Cannot delete a purchase order line which is in state \'%s\'.') %(line.state,))
            for proc in line.procurement_ids:
                proc.message_post(body=_('Purchase order line deleted.'))
            line.procurement_ids.filtered(lambda r: r.state != 'cancel').write({'state': 'exception'})
        return super(PurchaseOrderLine, self).unlink()
    @api.model
    def _get_date_planned(self, seller, po=False):