BUG: scalar assignment of a tz-aware is object dtype #19843
Description
[3] should be a datetime64[ns, UTC]
In [1]: df = pd.DataFrame({'A': [0, 1]}) In [3]: df['now'] = pd.Timestamp('20130101', tz='UTC') In [4]: df Out[4]: A now 0 0 2013-01-01 00:00:00+00:00 1 1 2013-01-01 00:00:00+00:00 In [5]: df.dtypes Out[5]: A int64 now object dtype: object In [6]: df['now2'] = pd.DatetimeIndex([pd.Timestamp('20130101', tz='UTC')]).repeat(len(df)) In [7]: df.dtypes Out[7]: A int64 now object now2 datetime64[ns, UTC] dtype: object