plugins/custom_forms/views/blocks/poll/_submission.html.erb
<% submission = form.submission_by(current_person) %>
<% if submission.try(:id).present? %>
<%= fields_for :block_submission, submission do |f| %>
<%= render partial: 'shared/form_submission',
locals: { f: f, form: form, submission: submission } %>
<% end %>
<% else %>
<%= render partial: 'shared/form',
locals: { form: form, submission: submission } %>
<% end %>