hehe/user/plugins/form/templates/forms/fields/avatar/avatar.html.twig

{% if form.data.avatar %}
    <label><img style="max-width:200px;" src="{{ base_url_simple ~ '/' ~ (form.data.avatar|first).path }}" /></label>
{% else %}
    <label><img src="https://www.gravatar.com/avatar/{{ form.data.email|md5 }}?s=200" /></label>
{% endif %}