patternlab-node: PL does not support twig extends

I am using Pattern Lab Node v2.6.1 on Mac, with Node v6.7, using the Gulp Edition.

Expected Behavior

when extending a template, it extend the template… it is referenced here too : https://github.com/pattern-lab/patternlab-node/issues/285

Actual Behavior

when extending, pl make it like including

Steps to Reproduce

x.twig

foo
{% block content %}
    bar
{% endblock %}

=> output foobar

y.twig

{% extends "x.twig" %}
foo
{% block content %}
    baz
{% endblock %}

=> output foobar to => should output foobaz

z.twig

{% extends "x.twig" %}
foo
{% block content %}
    {{ parent() }}
    baz
{% endblock %}

=> output foobarbar => should output foobarbaz