BUG: (GH3997) Fix for dropna=False in stack
Merge pull request #3999 from mtkni/stack_dropna

BUG: (GH3997) Fix for dropna=False in stack
Fix rename for MultiIndex columns DataFrame

Fix rename for MultiIndex columns DataFrame
Add a release note for #4004
Merge pull request #4004 from ogiaquino/Fix_rename_for_MultiIndex_columns_DataFrame

Fix rename for MultiIndex columns DataFrame
FIX groupby name without multiindex GH4014
Merge pull request #4015 from hayd/GH4104_groupby_index_name

FIX groupby name without multiindex GH4104