stock_inventory_ean13/stock_inventory_product_ean13.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>

        <record model="ir.ui.view" id="stock_inventory_ean13">
            <field name="name">stock.inventory.ean13</field>
            <field name="model">stock.inventory</field>
            <field name="inherit_id" ref="stock.view_inventory_form"/>
            <field name="arch" type="xml">
                <xpath expr="//tree[@string='Inventory Details']//field[@name='product_id']" position="after">
                    <field name="ean13"/>
                </xpath>
            </field>
        </record>
        
   </data>
</openerp>