BUG: diff on a DataFrame with a datelike broken

[jreback]

In [10]: df = DataFrame(dict(time = [Timestamp('20130101 9:01'),Timestamp('20130101 9:02')],value=[1.0,2.0]))

In [11]: df
Out[11]: 
                 time  value
0 2013-01-01 09:01:00      1
1 2013-01-01 09:02:00      2

works on series

In [12]: df.time.diff()
Out[12]: 
0        NaT
1   00:01:00
Name: time, dtype: timedelta64[ns]

Broken with a datelike dtype inclded

In [13]: df.diff()
ValueError: cannot include dtype 'm' in a buffer

[jreback]

work-around is:

df.apply(Series.diff)