Django Wagtail Jinja2 include\u块标记不传递变量

我有以下非常简单的语句来渲染wagtail中的块。

{% for block in blocks %}
    {% include_block block %}
{% endfor %}

{% set background_image = block.background_image.image %}

在由include\u块调用的模板中调用的上述语句引发以下错误。

'block' is undefined

http://docs.wagtail.io/en/v1.9/advanced_topics/jinja2.html#include-block

为了显式传递变量,我有以下语句,但它仍然不起作用,

 {% include_block block with context %}