Unit Test Mysteriously Failed
Travis got the following on Python 2.7 `NOSE_ARGS="slow and not network" LOCALE_OVERRIDE="zh_CN.GB18030" FULL_DEPS=true JOB_TAG=_LOCALE JOB_NAME=27_slow_nnet_LOCALE`:

```
======================================================================
FAIL: test_partially_invalid_plot_data (pandas.tests.test_graphics.TestDataFramePlots)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas/tests/test_graphics.py", line 952, in test_partially_invalid_plot_data
    df.plot(kind=kind)
  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas/util/testing.py", line 1320, in __exit__
    raise AssertionError("{0} not raised.".format(name))
AssertionError: TypeError not raised.
```

When I re-ran test, it passed.
