Remove code that is not needed once python 2.6 is our minimal version.

IPython/testing/ipunittest.py

@@ -39,11 +39,7 b' from __future__ import absolute_import'
 import re
 import sys
 import unittest
-from doctest import DocTestFinder, DocTestRunner
-try:
-    from doctest import TestResults
-except:
-    from ._doctest26 import TestResults
+from doctest import DocTestFinder, DocTestRunner, TestResults
 
 # We already have python3-compliant code for parametric tests
 if sys.version[0]=='2':