use get_user_model

pandora/archive/models.py

@@ -9,7 +9,7 @@ import time
 
 from six import string_types, PY2
 from django.conf import settings
-from django.contrib.auth.models import User
+from django.contrib.auth import get_user_model
 from django.db import models
 from django.db.models.signals import pre_delete
 from django.utils.encoding import python_2_unicode_compatible
@@ -28,6 +28,8 @@ from .chunk import save_chunk
 from . import extract
 from . import managers
 
+User = get_user_model()
+
 if not PY2:
     unicode = str