{% for key, child in form %}
    {% if key != "placeholder" %}
        {{ key }}
    {% endif %}
{% endfor %}
{# returns 1 2 3 4 5 6 7 8 9 #}
{# expected 0 1 2 3 4 5 6 7 8 9 #}

{% for key, child in form %}
    {{ key }}
{% endfor %}
{# returns placeholder 0 1 2 3 4 5 6 7 8 9 #}