Fix thread stop for Py3

test.py

@@ -29,6 +29,7 @@ import unittest
 from optparse import OptionParser
 import paramiko
 import threading
+from paramiko.py3compat import PY3
 
 sys.path.append('tests')
 
@@ -148,6 +149,9 @@ def main():
     # TODO: make that not a problem, jeez
     for thread in threading.enumerate():
         if thread is not threading.currentThread():
+            if PY3:
+                thread._stop()
+            else:
                 thread._Thread__stop()
     # Exit correctly
     if not result.wasSuccessful():