Splitted from #11351. `Series.append` with `DatetimeBlock` and `DatetimeTZBlock` raises `AttributeError`. ``` import pandas as pd s = pd.Series([pd.Timestamp('2011-01-01'), pd.NaT]) s #0 2011-01-01 #1 NaT # dtype: datetime64[ns] stz = pd.Series(pd.DatetimeIndex(['2012-01-01', '2012-01-02'], tz='Asia/Tokyo')) stz #0 2012-01-01 00:00:00+09:00 #1 2012-01-02 00:00:00+09:00 # dtype: datetime64[ns, Asia/Tokyo] s.append(stz) # AttributeError: 'numpy.ndarray' object has no attribute 'tz_localize' ```