pydata/pandas — pull request #5305 by jreback (2013-10-23 23:55:58+00:00)
Title: ENH: allow astype conversions for timedeltas to other timedelta freqs (still returns a float series), related to GH4521

related #4521

```
In [4]: td = pd.to_timedelta([0,1,2],unit='D')

In [5]: td
Out[5]:
0 00:00:00
1 1 days, 00:00:00
2 2 days, 00:00:00
dtype: timedelta64[ns]

In [6]: td / np.timedelta64(1,'s')
Out[6]:
0 0
1 86400
2 172800
dtype: float64
```

This is new (used to raise)
```
In [7]: td.astype('timedelta64[s]')
Out[7]:
0 0
1 86400
2 172800
dtype: float64
```