title: How to fix django admin foreign key display that used raw_id_fields
body: <p>I have recently migrated a website from Django 1.6 to Django 1.8 and I can't figure out the simple way to fix the behaviour of django admin when it displays foreignkey fields that use the "raw_id_fields" in the adminClass.</p>
  
  <p>The use case is exactly the one from django book : <a href="http://www.djangobook.com/en/2.0/chapter06.html" rel="nofollow">http://www.djangobook.com/en/2.0/chapter06.html</a> (Figure 6-14)</p>
  
  <pre><code>class BookAdmin(admin.ModelAdmin):
      ...
      raw_id_fields = ('publisher',)
  </code></pre>
  
  <p>Administration display used to have a spyglass at the end allowing to pick a new foreignkey id, but now none is displayed.</p>
  
  <p>Documentation hint's at some new mechanism but it's unclear how to apply it here:
  <a href="https://docs.djangoproject.com/en/1.8/ref/contrib/admin/#django.contrib.admin.ModelAdmin.formfield_overrides" rel="nofollow">https://docs.djangoproject.com/en/1.8/ref/contrib/admin/#django.contrib.admin.ModelAdmin.formfield_overrides</a></p>
  
  <p>Thanks</p>