sale_exceptions/sale_workflow.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>
        <record id="sale.trans_draft_router" model="workflow.transition">
            <field name="signal">order_confirm</field>
            <field name="condition">test_exceptions()</field>
        </record>
        <record id="sale.trans_sent_router" model="workflow.transition">
            <field name="signal">order_confirm</field>
            <field name="condition">test_exceptions()</field>
        </record>
    </data>
</openerp>