related #5690 This works: ``` pd.Series(np.array([np.timedelta64(300000000)])) ``` ``` 0 00:00:00.300000 dtype: timedelta64 ``` but this does not: ``` pd.Series([np.timedelta64(300000000)]) ``` on Numpy 1.7: ``` TypeError: don't know how to convert scalar number to float ``` and on Numpy 1.8: ``` 0 300000000 dtype: int64 ```