add missing import

Gauvain Pocentek · Gauvain Pocentek · commit 9c74442f8ad3 · 2016-01-09T11:52:26.000+01:00
diff --git a/gitlab/objects.py b/gitlab/objects.py
@@ -21,6 +21,7 @@
 import itertools
 import json
 import sys
+import warnings
 
 import six
 
