BUG: Corrects an index error in blaze loader.

Fixes the case where a delta has an asof_date of the last requested
day and an index error would occur. This guards against this
specifically to make the delta be effective through the end of the
requested window.

Adds a test case for this behavior.

tests/pipeline/test_blaze.py

@@ -399,7 +399,7 @@ class BlazeToPipelineTestCase(TestCase):
     @with_extra_sid
     def test_deltas(self, asset_info):
         expr = bz.Data(self.df, name='expr', dshape=self.dshape)
-        deltas = bz.Data(self.df.iloc[:-3], name='deltas', dshape=self.dshape)
+        deltas = bz.Data(self.df, name='deltas', dshape=self.dshape)
         deltas = bz.transform(
             deltas,
             value=deltas.value + 10,
@@ -411,6 +411,8 @@ class BlazeToPipelineTestCase(TestCase):
                                     [1.0, 2.0, 3.0]]),
             '2014-01-03': np.array([[11.0, 12.0, 13.0],
                                     [2.0, 3.0, 4.0]]),
+            '2014-01-04': np.array([[12.0, 13.0, 14.0],
+                                    [12.0, 13.0, 14.0]]),
         })
 
         nassets = len(asset_info)
@@ -422,7 +424,7 @@ class BlazeToPipelineTestCase(TestCase):
 
         with tmp_asset_finder(asset_info) as finder:
             expected_output = pd.DataFrame(
-                list(concatv([12] * nassets, [13] * nassets)),
+                list(concatv([12] * nassets, [13] * nassets, [14] * nassets)),
                 index=pd.MultiIndex.from_product((
                     sorted(expected_views.keys()),
                     finder.retrieve_all(asset_info.index),
@@ -430,6 +432,7 @@ class BlazeToPipelineTestCase(TestCase):
                 columns=('value',),
             )
             dates = self.dates
+            dates = dates.insert(len(dates), dates[-1] + timedelta(days=1))
             self._run_pipeline(
                 expr,
                 deltas,