I have the following template:

<t t-name='test_template'>
     <t t-call="other_template"/>
</t>

And I have the following code:

alert(data['items'].length);
var html = $(this.qweb.render("test_template", {'data' : data}));
alert(data['items'].length);

The first alert is showing 30. The second one is showing 1.

Why is the template renderer changing the object reference passed as data?

This only happens when using sub-template calling.