pydata/pandas — pull request #4302 by jreback (2013-07-20 00:38:24+00:00)
Title: BUG: explicity change nan -> NaT when assigning to datelike dtypes

closes #4292

essentially was doing a assignment of ``np.nan`` to a numpy array of dtype ``datetime64[ns]``
which works correct (set's the value to ``iNaT``) on little endian, for some reason on big
endian doesn't work, explicity change the ``nan`` to ``iNaT``