importing pandas 0.9 breaks matplotlib plot_date
```
import datetime
import sys
import numpy
from matplotlib import pyplot

import pandas;print(pandas.__version__); #comment out this line to have it work

fig = pyplot.figure()
ax = fig.add_subplot(1, 1, 1)
dates = [datetime.date(2008, 12, 31), datetime.date(2009, 1, 31)]
values1 = numpy.arange(10.0, 11.0, 0.5)
values2 = numpy.arange(11.0, 12.0, 0.5)
kw = dict(fmt='-', lw=4)
ax.plot_date([x.toordinal() for x in dates], values1, **kw)
ax.plot_date([x.toordinal() for x in dates], values2, **kw)
fig.show()

raw_input("press 'enter' to end")
```
