title: if domain returned from onchange field has no selection values
body: <p>I want to put domain on Sales Person() that only Sales person for selected Sales Team should be displayed.</p>
  
  <p>For that I have created on_change() on section_id(sales team) and I am returning domain from that method. Though domain is displayed on Sales Person(user_id) when I go to developer mode but no value is displayed over there.</p>
  
  <p>Here is code:</p>
  
  <pre><code>def onchange_section_id(self, cr, uid, ids, section_id, context=None):
      crm_case_section_obj = self.pool.get('crm.case.section')
      member_ids = []
      if section_id:
          member_ids = [member_id.id for member_id in crm_case_section_obj.browse(cr, uid, section_id, context=context).member_ids]
      return {'domain': {'user_id': [('user_id', 'in', member_ids)]}}
  </code></pre>
  
  <p>Am i missing something?</p>
  
  <p>Thanx in advance.</p>