Prevent broken Personas from raising an exception

If the Persona does not exist, raise a 404 in the legacy site.

src/olympia/addons/serializers.py

@@ -455,10 +455,9 @@ class AddonSerializer(serializers.ModelSerializer):
         something on the Persona instance, explicitly or not, to avoid 500
         errors and/or SQL queries in ESAddonSerializer."""
         try:
-            # Sadly, https://code.djangoproject.com/ticket/14368 prevents us
-            # from setting obj.persona = None in ESAddonSerializer.fake_object
-            # below. This is fixed in Django 1.9, but in the meantime we work
-            # around it by creating a Persona instance with a custom '_broken'
+            # Setting obj.persona = None in ESAddonSerializer.fake_object()
+            # below sadly isn't enough, so we work around it in that method by
+            # creating a Persona instance with a custom '_broken'
             # attribute indicating that it should not be used.
             if obj.type == amo.ADDON_PERSONA and (
                     obj.persona is None or hasattr(obj.persona, '_broken')):
@@ -646,11 +645,10 @@ class ESAddonSerializer(BaseESSerializer, AddonSerializer):
                     popularity=data.get('average_daily_users'),
                 )
             else:
-                # Sadly, https://code.djangoproject.com/ticket/14368 prevents
-                # us from setting obj.persona = None. This is fixed in
-                # Django 1.9, but in the meantime, work around it by creating
-                # a Persona instance with a custom attribute indicating that
-                # it should not be used.
+                # Sadly, although we can set obj.persona = None, this does not
+                # seem to prevent the query later on. So instead, work around
+                # it by creating a Persona instance with a custom attribute
+                # indicating that it should not be used.
                 obj.persona = Persona()
                 obj.persona._broken = True
 

src/olympia/addons/tests/test_views.py

@@ -378,6 +378,12 @@ class TestDetailPage(TestCase):
         assert response.status_code == 200
         assert response.context['addon'].id == 15663
 
+    def test_broken_persona(self):
+        persona = Persona.objects.get(addon_id=15663)
+        persona.delete()
+        response = self.client.get(reverse('addons.detail', args=['a15663']))
+        assert response.status_code == 404
+
     def test_review_microdata_personas(self):
         a = Addon.objects.get(id=15663)
         a.name = '<script>alert("fff")</script>'

src/olympia/addons/views.py

@@ -153,7 +153,10 @@ def persona_detail(request, addon):
     if not (addon.is_public() or addon.is_pending()):
         raise http.Http404
 
-    persona = addon.persona
+    try:
+        persona = addon.persona
+    except Persona.DoesNotExist:
+        raise http.Http404
 
     # This persona's categories.
     categories = addon.categories.all()