Don't install the KnownFailure nosetest plugin as a pkg_resources entry_point, as it can, under some circumstances, conflict with the one in IPython. This means that the supported method to run the tests is from the tests.py script or import matplotlib; matplotlib.test().

Author: mdboom

setup.py

@@ -229,10 +229,4 @@
           # check for zip safety.
           zip_safe=False,
 
-          # Install our nose plugin so it will always be found
-          entry_points={
-              'nose.plugins.0.10': [
-                  'KnownFailure = matplotlib.testing.noseclasses:KnownFailure'
-                ]
-            },
          )