Address comments.

Author: Ben Kandel

pandas/core/indexing.py

@@ -1463,7 +1463,7 @@ def _getitem_axis(self, key, axis=0):
                         not isinstance(key[0], tuple)):
                     if isinstance(key, ABCSeries):
                         # GH 14730
-                        key = key.values.tolist()
+                        key = list(key)
                     key = tuple([key])
 
             # an iterable multi-selection

pandas/tests/indexes/test_multi.py

@@ -12,7 +12,7 @@
 
 import pandas as pd
 
-from pandas import (CategoricalIndex, DataFrame, Index, MultiIndex, Series,
+from pandas import (CategoricalIndex, DataFrame, Index, MultiIndex,
                     compat, date_range, period_range)
 from pandas.compat import PY3, long, lrange, lzip, range, u
 from pandas.core.common import PerformanceWarning, UnsortedIndexError
@@ -346,19 +346,6 @@ def test_set_levels_labels_names_bad_input(self):
         with tm.assertRaisesRegexp(TypeError, 'string'):
             self.index.set_names(names, level=0)
 
-    def test_series_index(self):
-        # GH14730
-        index = MultiIndex.from_product([[1, 2, 3], ['A', 'B', 'C']])
-        x = Series(index=index, data=range(9))
-        y = Series([1, 3])
-        expected = Series(
-            data=[0, 1, 2, 6, 7, 8],
-            index=MultiIndex.from_product([[1, 3], ['A', 'B', 'C']]))
-        actual_from_series = x.loc[y]
-        actual_from_list = x.loc[[1, 3]]
-        tm.assert_series_equal(expected, actual_from_list)
-        tm.assert_series_equal(expected, actual_from_series)
-
     def test_set_levels_categorical(self):
         # GH13854
         index = MultiIndex.from_arrays([list("xyzx"), [0, 1, 2, 3]])

pandas/tests/test_multilevel.py

@@ -690,6 +690,25 @@ def test_getitem_partial(self):
         expected.columns = expected.columns.droplevel(0).droplevel(0)
         assert_frame_equal(result, expected)
 
+    def test_series_index(self):
+        # GH14730
+        index = MultiIndex.from_product([[1, 2, 3], ['A', 'B', 'C']])
+        x = Series(index=index, data=range(9), dtype=np.float64)
+        y = Series([1, 3])
+        expected = Series(
+            data=[0, 1, 2, 6, 7, 8],
+            index=MultiIndex.from_product([[1, 3], ['A', 'B', 'C']]),
+            dtype=np.float64)
+        result = x.loc[y]
+        result2 = x.loc[[1, 3]]
+        tm.assert_series_equal(result, expected)
+        tm.assert_series_equal(result2, expected)
+        empty_series = Series(data=[], dtype=np.float64)
+        expected2 = Series([], index=MultiIndex(
+            levels=index.levels, labels=[[], []], dtype=np.float64))
+        result3 = x.loc[empty_series]
+        tm.assert_series_equal(result3, expected2)
+
     def test_getitem_slice_not_sorted(self):
         df = self.frame.sortlevel(1).T