HIVE-8774 Fix groupBy index optimization (Pengcheng Xiong via Laljo John Pullokkaran)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1643732 13f79535-47bb-0310-9956-ffa450edef68
Rolled back to 1643551

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1643736 13f79535-47bb-0310-9956-ffa450edef68