pydata/pandas — pull request #3152 by jreback (2013-03-23 22:09:03+00:00)
Title: BUG: GH2763 fixed downcasting of groupby results on SeriesGroupBy

closes #2763
e.g. was returning float64 on int64 input when possible to preserve
in first/last

more general cases were fixed in prior PRs (e.g. #3041)