|shuffle filter doesn't work

[bobdenotter]

This ought to work:

    {% setcontent pages = "pages" limit 4  %}

    {% for page in pages|shuffle %}
        <li>{{ page.id }} - {{ page|title }}</li>
    {% endfor %}

But, it throws an exception instead:

We should ensure the |shuffle filter works on Pagerfanta objects, as well as regular arrays.

Additionally, check if this also applies to sort, first, last, batch, length (does work, but wrong results), reverse and slice.

[I-Valchev]

Afaik, only |length doesn't work. The rest seemed to work fine for me. #1633 fixes length and shuffle.