BUG: Fixed to_datetime for array with both Tz-aware datetimes and NaTs

doc/source/release.rst

@@ -110,6 +110,7 @@ Bug Fixes
     ``MultiIndex`` (:issue:`5402`).
   - Bug in ``pd.read_msgpack`` with inferring a ``DateTimeIndex`` frequencey
     incorrectly (:issue:`5947`)
+  - Fixed ``to_datetime`` for array with both Tz-aware datetimes and ``NaT``s  (:issue:`5961`)
 
 pandas 0.13.0
 -------------

pandas/tseries/tests/test_timezones.py

@@ -10,7 +10,7 @@
 from pandas import (Index, Series, TimeSeries, DataFrame, isnull,
                     date_range, Timestamp)
 
-from pandas import DatetimeIndex, Int64Index, to_datetime
+from pandas import DatetimeIndex, Int64Index, to_datetime, NaT
 
 from pandas.core.daterange import DateRange
 import pandas.core.datetools as datetools
@@ -671,6 +671,12 @@ def test_datetimeindex_tz(self):
         for other in [idx2, idx3, idx4]:
             self.assert_(idx1.equals(other))
 
+    def test_datetimeindex_tz_nat(self):
+        idx = to_datetime([Timestamp("2013-1-1", tz='US/Eastern'), NaT])
+
+        self.assertTrue(isnull(idx[1]))
+        self.assertTrue(idx[0].tzinfo is not None)
+
 
 class TestTimeZones(tm.TestCase):
     _multiprocess_can_split_ = True

pandas/tslib.pyx

@@ -933,7 +933,7 @@ def datetime_to_datetime64(ndarray[object] values):
     iresult = result.view('i8')
     for i in range(n):
         val = values[i]
-        if util._checknull(val):
+        if util._checknull(val) or val is NaT:
             iresult[i] = iNaT
         elif PyDateTime_Check(val):
             if val.tzinfo is not None: