title: Django Combining __unaccent and __search Lookups
body: <p>So I am trying to use <code>__unaccent</code> and <code>__search</code> in the same model filter, but I receive an error when doing so. I am trying to make a filter using the term "Pokemon" match the term "Pokémon" (notice the "é")</p>
  
  <p><code>Game.objects.filter(title__unaccent__icontains="Pokemon")</code> works fine, but when I use <code>Game.objects.filter(title__unaccent__search="Pokemon)</code>, I get the following error:</p>
  
  <blockquote>
    <p>ProgrammingError at /autocomplete-games/ function unaccent(tsquery)</p>
    
    <p>does not exist LINE 1: ...ALESCE(UNACCENT("main_game"."title"), ''))
    @@ (UNACCENT(p...
                                                                 ^ HINT:  No function matches the given name and argument types. You might need
    to add explicit type casts.</p>
  </blockquote>
  
  <p>I am using:</p>
  
  <p>Python 3.5</p>
  
  <p>Django 1.10</p>
  
  <p>PostgreSQL (unaccent extension installed)</p>