title: Django choicefield iniital value problem
body: <p>I have a dynamic choice field:</p>
  
  <pre><code>PASSENGER_TYPE_CHOICE = [(p.id, p.cabin.name) for p in flight.passengertype_set.all() if p.availableSeats &gt; 0]
  self.fields['passenger_type'] = forms.ChoiceField(label=str(self.flight.code)+" Seat Type", initial=PASSENGER_TYPE_CHOICE[0][0],choices=PASSENGER_TYPE_CHOICE)
  </code></pre>
  
  <p>Notice that I put an initial value for it. But when I click the submit button for this form, it raises "This field is required". When I click the choicefield and select an option, it works. But do i really have to select first, even when there is an initial value? Please help?</p>