Test failure with matplotlib 1.5.2rc2 on Debian
When running the test suite after the package was built, we get the following failure:

```
ERROR: test_plot (pandas.tests.test_graphics.TestDataFramePlots)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/$BUILD/debian/tmp/usr/lib/python2.7/dist-packages/pandas/tests/test_graphics.py", line 1322, in test_plot
    df.plot.line(blarg=True)
  File "/$BUILD/debian/tmp/usr/lib/python2.7/dist-packages/pandas/tools/plotting.py", line 3758, in line
    return self(kind='line', x=x, y=y, **kwds)
[...]
  File "/$BUILD/debian/tmp/usr/lib/python2.7/dist-packages/pandas/tools/plotting.py", line 1340, in _plot
    return ax.plot(*args, **kwds)
  File "/usr/lib/python2.7/dist-packages/matplotlib/__init__.py", line 1821, in inner
    return func(ax, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/matplotlib/axes/_axes.py", line 1432, in plot
    for line in self._get_lines(*args, **kwargs):
  File "/usr/lib/python2.7/dist-packages/matplotlib/axes/_base.py", line 381, in _grab_next_args
    for seg in self._plot_args(remaining, kwargs):
  File "/usr/lib/python2.7/dist-packages/matplotlib/axes/_base.py", line 369, in _plot_args
    seg = func(x[:, j % ncx], y[:, j % ncy], kw, kwargs)
  File "/usr/lib/python2.7/dist-packages/matplotlib/axes/_base.py", line 276, in _makeline
    seg = mlines.Line2D(x, y, **kw)
  File "/usr/lib/python2.7/dist-packages/matplotlib/lines.py", line 380, in __init__
    self.update(kwargs)
  File "/usr/lib/python2.7/dist-packages/matplotlib/artist.py", line 859, in update
    raise AttributeError('Unknown property %s' % k)
AttributeError: Unknown property blarg
```

Full log [here](https://tests.reproducible-builds.org/debian/rbuild/testing/amd64/pandas_0.18.0+git114-g6c692ae-1.rbuild.log) (from the [Debian bug report](https://bugs.debian.org/827938)).

`pandas.show_versions()` gives:

```
INSTALLED VERSIONS
------------------
commit: None
python: 2.7.12.final.0
python-bits: 64
OS: Linux
OS-release: 4.6.0-1-amd64
machine: x86_64
processor: 
byteorder: little
LC_ALL: C
LANG: C

pandas: 0.18.0+git114-g6c692ae
nose: 1.3.7
pip: None
setuptools: 20.10.1
Cython: None
numpy: 1.11.1rc1
scipy: 0.17.1
statsmodels: 0.6.1
xarray: None
IPython: None
sphinx: 1.4.4
patsy: 0.4.1
dateutil: 2.4.2
pytz: 2015.7
blosc: None
bottleneck: None
tables: 3.2.2
numexpr: 2.6.0
matplotlib: 1.5.2rc2
openpyxl: 2.3.0
xlrd: 1.0.0
xlwt: 0.7.5
xlsxwriter: None
lxml: 3.6.0
bs4: 4.4.1
html5lib: 0.999
httplib2: None
apiclient: None
sqlalchemy: None
pymysql: None
psycopg2: None
jinja2: 2.8
boto: None
pandas_datareader: None
```
