ENH: add nlargest/nsmallest to Series groupby
Merge pull request #7356 from cpcloud/groupby-nlarg-smal-7053

ENH/GBY: add nlargest/nsmallest to Series.groupby
BUG: ix should return a Series for duplicate indices (GH7150)
Merge pull request #7402 from jreback/ix_series

BUG: ix should return a Series for duplicate indices (GH7150)