Minor correction to previous submit

Author: ri938

pandas/core/indexes/category.py

@@ -420,7 +420,7 @@ def reindex(self, target, method=None, level=None, limit=None,
 
         indexer, missing = self.get_indexer_non_unique(np.array(target))
 
-        if len(indexer):
+        if len(self.codes):
             new_target = self.take(indexer)
         else:
             new_target = target