Issue #27030: Merge RE fix from 3.5

diff --cc Lib/lib2to3/tests/test_refactor.py
index ab5ce72793c48d8530178bfb59f13faf5d85081d,856300153ddc4d624dd4ee8e64f01640e9bd06ae..94dc135fac235aa1717515019146998ec55ffba3
--- 1/Lib/lib2to3/tests/test_refactor.py
--- 2/Lib/lib2to3/tests/test_refactor.py
+++ b/Lib/lib2to3/tests/test_refactor.py
@@@ -7,7 -7,9 +7,8 @@@ from __future__ import with_statemen
  import sys
  import os
  import codecs
 -import operator
  import io
+ import re
  import tempfile
  import shutil
  import unittest