Do not log out already logged out users

backend/auth.py

@@ -34,7 +34,8 @@ class DACSRemoteUserMiddleware(django.contrib.auth.middleware.RemoteUserMiddlewa
             # AuthenticationMiddleware).
 
             # Actually, make really sure we are logged out!
-            auth.logout(request)
+            if request.user.is_authenticated():
+                auth.logout(request)
             return
         # If the user is already authenticated and that user is the user we are
         # getting passed in the headers, then the correct user is already