statsmodels/statsmodels — pull request #1986 by josef-pkt (2014-09-22 18:45:45+00:00)
Title: Bug multicomp 1927 rebased

This takes over from PR #1927
see comments there

move check for at least two groups to use groupunique

ENH: allow group_order to select a subsets of labels in the data.
This was a bug and is now a feature.
The way the labels were initialized, the missing labels were assigned integer label 0.