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

    <template id="test_website.test_template" name="test template 2">
&lt;!DOCTYPE html&gt;
<html>
    <head>
        <t t-call-assets="test_website.test_bundle" t-js="False"/>
        <meta/>
        <t t-call-assets="test_website.test_bundle" t-css="False"/>
    </head>
    <body>
        <img src="http://test.external.link/img.png"/>
        <img src="/test_website/static/img.png"/>
        <a href="http://test.external.link/link">x</a>
        <a href="/web/content/local_link">x</a>
        <span t-attf-style="background-image: url('/web/image/2')" t-att-empty="False">xxx</span>
        <div widget="html" t-field="user.signature"/>
        <div widget="image" t-field="user.avatar_1920" t-options="{'widget': 'image'}"/>
    </body>
</html>
    </template>

    <template id="test_website.test_template_tatt_qweb" name="t-att template">
        <a t-att-href='"/"'>1</a>
        <a t-att-href='False'>2</a>
        <a t-att-href='None'>3</a>
        <a t-att-href=''>4</a>
        <a t-att-href='""'>5</a>
    </template>

</odoo>