title: Checkbox not working in a Django form (bug?)
body: <p>In <a href="https://github.com/vporton/django-checkbox-bug" rel="nofollow noreferrer">this Django program</a> the checkbox in the form is not shown. I want to show it.</p>
  
  <p>Please explain what is my error.</p>
  
  <p>Django version 1.10.3.</p>
  
  <p>I tried to render the form this way:</p>
  
  <pre><code>class MyForm(forms.Form):
      name = forms.CharField(label='Organization name')
      email = forms.EmailField(label='Organization email')
      trial_period = forms.CheckboxInput()
  
  # The view method
  def test(request):
      return HttpResponse(str(checkbox_test.forms.MyForm()))
  </code></pre>
  
  <p>The view shows name and email but no checkbox for <code>trial_period</code>.</p>