BUG: Series.ffill() with mixed dtypes containing tz-aware datetimes fails. (GH14956)

Author: Adrian

doc/source/whatsnew/v0.20.0.txt

@@ -300,3 +300,4 @@ Bug Fixes
 - Bug in ``Series.unique()`` in which unsigned 64-bit integers were causing overflow (:issue:`14721`)
 - Require at least 0.23 version of cython to avoid problems with character encodings (:issue:`14699`)
 - Bug in converting object elements of array-like objects to unsigned 64-bit integers (:issue:`4471`)
+- Bug in Series.ffill() with mixed dtypes containing tz-aware datetimes. (:issue: `14956`)

pandas/src/inference.pyx

@@ -859,7 +859,7 @@ def maybe_convert_objects(ndarray[object] objects, bint try_float=0,
 
     # we try to coerce datetime w/tz but must all have the same tz
     if seen_datetimetz:
-        if len(set([ getattr(val, 'tz', None) for val in objects ])) == 1:
+        if len(set([getattr(val, 'tzinfo', None) for val in objects])) == 1:
             from pandas import DatetimeIndex
             return DatetimeIndex(objects)
         seen_object = 1