Those two patches on their own don't break anything, but the combination will break posixGroups implementation as it stands.
My patch corrects that.
I'm new to patches in Hadoop, what additional work is required on the patch?
For testing, I've run it on a cluster and verified I see the right thing when configured in posixGroups mode with the 'groups' command. I'm not 100% sure how to modify the unit tests to fit this case, but haven't looked very deeply yet.