comment and reversion

pandas-dev · jreback · Oct 28, 2018 · Oct 17, 2018 · Oct 17, 2018 · Oct 17, 2018
commit af4872ea9b472684d76621e6779bd6b3104af8cc
diff --git a/pandas/core/arrays/datetimelike.py b/pandas/core/arrays/datetimelike.py
@@ -352,7 +352,7 @@ def _add_offset(self, offset):
     def _add_delta(self, other):
         """
         Add a timedelta-like, Tick or TimedeltaIndex-like object
-        to self.
+        to self, yielding another array of the same type
 
         Parameters
         ----------

diff --git a/pandas/core/arrays/datetimes.py b/pandas/core/arrays/datetimes.py
@@ -487,7 +487,15 @@ def _sub_datelike(self, other):
     @Appender(dtl.DatetimeLikeArrayMixin._add_delta.__doc__)
     def _add_delta(self, delta):
         new_values = dtl.DatetimeLikeArrayMixin._add_delta(self, delta)
-        return type(self)(new_values, tz=self.tz, freq='infer')
+
+        # Note: this construction is _not_ equivalent to
+        #  type(self)(new_values, tz=self.tz, freq'infer'')
+        #  see GH#23215
+        tz = 'UTC' if self.tz is not None else None
+        result = type(self)(new_values, tz=tz, freq='infer')
+        if self.tz is not None and self.tz is not utc:
+            result = result.tz_convert(self.tz)
+        return result
 
     # -----------------------------------------------------------------
     # Timezone Conversion and Localization Methods