TST: set object dtype

Author: TomAugspurger

pandas/tests/reshape/test_concat.py

@@ -680,7 +680,7 @@ def test_concat_categorical_empty(self):
         tm.assert_series_equal(s1.append(s2, ignore_index=True), s2)
 
         s1 = pd.Series([], dtype='category')
-        s2 = pd.Series([])
+        s2 = pd.Series([], dtype='object')
 
         # different dtype => not-category
         tm.assert_series_equal(pd.concat([s1, s2], ignore_index=True), s2)