Undo change to merge.py and make whatsnew a 2 line comment.

Author: Dr-Irv

doc/source/whatsnew/v0.20.0.txt

@@ -351,7 +351,8 @@ Bug Fixes
 - Bug in converting object elements of array-like objects to unsigned 64-bit integers (:issue:`4471`, :issue:`14982`)
 - Bug in ``pd.pivot_table()`` where no error was raised when values argument was not in the columns (:issue:`14938`)
 
-- Bug in ``DataFrame.groupby().describe()`` when grouping on ``Index`` containing tuples. Raise `ValueError` if creating an `Index` with tuples and not passing a list of names (:issue:`14848`)
+- Bug in ``DataFrame.groupby().describe()`` when grouping on ``Index`` containing tuples (:issue:`14848`)
+- Raise `ValueError` if creating a `MultiIndex` with tuples and not passing a list of names (:issue:`15110`)
 
 
 

pandas/tools/merge.py

@@ -1626,11 +1626,7 @@ def __init__(self, objs, axis=0, join='outer', join_axes=None,
                 clean_objs.append(v)
             objs = clean_objs
             name = getattr(keys, 'name', None)
-            # GH 14848
-            # If you already have an Index, no need
-            # to recreate it
-            if not isinstance(keys, Index):
-                keys = Index(clean_keys, name=name)
+            keys = Index(clean_keys, name=name)
 
         if len(objs) == 0:
             raise ValueError('All objects passed were None')