JuliaStats/DataFrames.jl — pull request #738 by tonyhffong (2014-12-05 12:55:02+00:00)
Title: test groupby on subdataframe

A project of mine relies on this working. I saw a TODO in subdataframe code mentioning that `nrow` would be removed, which may have knock-on effect on `groupby`. This makes sure we navigate this properly.