Fix the with_poll tests for platforms without poll.  missing import.
diff --git a/Lib/test/test_telnetlib.py b/Lib/test/test_telnetlib.py
index 38da08c..5ccde23 100644
--- a/Lib/test/test_telnetlib.py
+++ b/Lib/test/test_telnetlib.py
@@ -4,6 +4,7 @@
 import time
 import contextlib
 
+import unittest
 from unittest import TestCase
 from test import support
 threading = support.import_module('threading')