The consequence of this commit is that variables are accessible that have been passed to a surrounding form helper.
Example template:
{% block my_widget_label %}
<label>{{ label }}
{% endblock %}
{% block my_widget_row %}
{# It is not necessary to explicitely pass through the label variable #}
{{ form_label(form) }}
{{ form_widget(form) }}
{% endblock %}
Example usage:
{{ form_row(form.mywidget, { 'label': 'My Widget' }) }}