BUG: fix lingering date_range over DST transition issue described in #1778

Author: wesm

pandas/tseries/index.py

@@ -298,7 +298,8 @@ def _generate(cls, start, end, periods, name, offset,
             else:
                 _normalized = _normalized and end.time() == _midnight
 
-        if hasattr(offset, 'delta'):
+
+        if hasattr(offset, 'delta') and offset != offsets.Day():
             if inferred_tz is None and tz is not None:
                 # naive dates
                 if start is not None and start.tz is None:

pandas/tseries/tests/test_timezones.py

@@ -426,11 +426,18 @@ def test_tzaware_datetime_to_index(self):
         self.assert_(index.tz.zone == 'US/Eastern')
 
     def test_date_range_span_dst_transition(self):
+        # #1778
+
+        # Standard -> Daylight Savings Time
         dr = date_range('03/06/2012 00:00', periods=200, freq='W-FRI',
                         tz='US/Eastern')
 
         self.assert_((dr.hour == 0).all())
 
+        dr = date_range('2012-11-02', periods=10, tz='US/Eastern')
+        self.assert_((dr.hour == 0).all())
+
+
 class TestTimeZones(unittest.TestCase):
 
     def setUp(self):