Removed duplicate code by moving changes to _AtIndexer._convert_key

 - More natural place for key modification to occur
 - __getitem__ and __setitem__ now remain essentially unchanged

Author: rhshadrach

pandas/core/indexing.py

@@ -2031,10 +2031,6 @@ def __getitem__(self, key):
                 raise ValueError("Invalid call for scalar access (getting)!")
 
         key = self._convert_key(key)
-
-        if isinstance(self.obj, ABCSeries) and len(key) > 1:
-            key = [key]
-
         return self.obj._get_value(*key, takeable=self._takeable)
 
     def __setitem__(self, key, value):
@@ -2046,13 +2042,9 @@ def __setitem__(self, key, value):
 
         if not isinstance(key, tuple):
             key = _tuplify(self.ndim, key)
-
-        if isinstance(self.obj, ABCSeries) and len(key) > 1:
-            key = [key]
-
+        key = list(self._convert_key(key, is_setter=True))
         if len(key) != self.ndim:
             raise ValueError("Not enough indexers for scalar access (setting)!")
-        key = list(self._convert_key(key, is_setter=True))
         self.obj._set_value(*key, value=value, takeable=self._takeable)
 
 
@@ -2065,6 +2057,11 @@ def _convert_key(self, key, is_setter: bool = False):
         Require they keys to be the same type as the index. (so we don't
         fallback)
         """
+        # For series, unpacking key needs to result in the label.
+        # This is already the case for non-multiindex
+        if isinstance(self.obj, ABCSeries) and len(key) > 1:
+            key = (key,)
+
         # allow arbitrary setting
         if is_setter:
             return list(key)