Fix an issue reauthing as a social auth user

If a social auth user is deleted and then attemnpts to relogin after the
old user object has been removed then it can cause an error.  So here
we'll add an extra lookup for the user just to verify

awx/main/middleware.py

@@ -5,7 +5,7 @@ import logging
 import threading
 import uuid
 
-from django.contrib.auth.models import User
+from django.contrib.auth.models import User, AnonymousUser
 from django.db.models.signals import post_save
 from django.db import IntegrityError
 from django.http import HttpResponseRedirect
@@ -62,7 +62,12 @@ class ActivityStreamMiddleware(threading.local):
     def set_actor(self, user, sender, instance, **kwargs):
         if sender == ActivityStream:
             if isinstance(user, User) and instance.actor is None:
-                instance.actor = user
+                user = User.objects.filter(id=user.id)
+                if user.exists():
+                    user = user[0]
+                    instance.actor = user
+                else:
+                    instance.actor = AnonymouseUser
                 instance.save(update_fields=['actor'])
             else:
                 if instance.id not in self.instance_ids: