Minor change in how to determined if sorting is needed

Author: nrebena

pandas/core/indexes/multi.py

@@ -3103,19 +3103,20 @@ def _reorder_indexer(
         -------
         indexer : a sorted Int64Index indexer of self ordered as seq
         """
-        # Find out if the list_like label are sorted as the levels or not
-        need_sort = False
-        for i, k in enumerate(seq):
-            if is_list_like(k):
-                if not need_sort:
-                    k_codes = self.levels[i].get_indexer(k)
-                    k_codes = k_codes[k_codes >= 0]  # Filter absent keys
-                    # True if the given codes are not ordered
-                    need_sort = (k_codes[:-1] > k_codes[1:]).any()
-        # Bail out if no need to sort
-        # This is only true for a lexsorted index
-        if not need_sort and self.is_lexsorted():
-            return indexer
+        # If the index is lexsorted and the list_like label in seq are sorted
+        # then we do not need to sort
+        if self.is_lexsorted():
+            need_sort = False
+            for i, k in enumerate(seq):
+                if is_list_like(k):
+                    if not need_sort:
+                        k_codes = self.levels[i].get_indexer(k)
+                        k_codes = k_codes[k_codes >= 0]  # Filter absent keys
+                        # True if the given codes are not ordered
+                        need_sort = (k_codes[:-1] > k_codes[1:]).any()
+            # Bail out if both index and seq are sorted
+            if not need_sort:
+                return indexer
 
         n = len(self)
         keys: Tuple[np.ndarray, ...] = tuple()