tests: lexicographical imports in silenttestrunner.py

tests/silenttestrunner.py

@@ -1,7 +1,7 b''
 from __future__ import absolute_import, print_function
+import os
+import sys
 import unittest
-import sys
-import os
 
 def main(modulename):
     '''run the tests found in module, printing nothing when all tests pass'''