Merge branch 'master' of https://github.com/pandas-dev/pandas into pi…

…_add

pandas/core/arrays/period.py

@@ -18,8 +18,8 @@
 from pandas.util._decorators import (cache_readonly, deprecate_kwarg)
 
 from pandas.core.dtypes.common import (
-    _TD_DTYPE,
-    is_integer_dtype, is_float_dtype, is_period_dtype, is_timedelta64_dtype)
+    is_integer_dtype, is_float_dtype, is_period_dtype, is_timedelta64_dtype,
+    is_datetime64_dtype, _TD_DTYPE)
 from pandas.core.dtypes.dtypes import PeriodDtype
 from pandas.core.dtypes.generic import ABCSeries
 
@@ -458,6 +458,8 @@ def _maybe_convert_timedelta(self, other):
         """
         if isinstance(
                 other, (timedelta, np.timedelta64, Tick, np.ndarray)):
+            # TODO: is the np.ndarray case still relevant now that Arithmetic
+            #  methods don't call this method?
             offset = frequencies.to_offset(self.freq.rule_code)
             if isinstance(offset, Tick):
                 # _check_timedeltalike_freq_compat will raise if incompatible
@@ -499,7 +501,7 @@ def _check_timedeltalike_freq_compat(self, other):
         else:
             # TimedeltaArray/Index
             nanos = other.asi8
-        
+
         if np.all(nanos % base_nanos == 0):
             # nanos being added is an integer multiple of the
             #  base-frequency to self.freq