fix 'sys not defined' error when displaying observer not installed warning

diff --git a/planetstack/core/models/user.py b/planetstack/core/models/user.py
index 42ea652..4f723b7 100644 (file)
--- a/planetstack/core/models/user.py
+++ b/planetstack/core/models/user.py
@@ -1,5 +1,6 @@
 import os
 import datetime
+import sys
 from collections import defaultdict
 from django.db import models
 from django.db.models import F, Q