Don't monkeypatch nose in Python 3, as it must be a newer version.

IPython/testing/nosepatch.py

@@ -17,6 +17,7 b' Note: merely importing this module causes the monkeypatch to be applied."""'
 #-----------------------------------------------------------------------------
 
 import unittest
+import sys
 import nose.loader
 from inspect import ismethod, isfunction
 
@@ -64,5 +65,7 b' def getTestCaseNames(self, testCaseClass):'
 
 ##########################################################################
 # Apply monkeypatch here
-nose.loader.TestLoader.getTestCaseNames = getTestCaseNames
+# Python 3 must be running with newer version of Nose, so don't touch anything.
+if sys.version_info[0] < 3:
+    nose.loader.TestLoader.getTestCaseNames = getTestCaseNames
 ##########################################################################