HIVE-8805: CBO skipped due to SemanticException: Line 0:-1 Both left and right aliases encountered in JOIN 'avg_cs_ext_discount_amt' (Laljo John Pullokkaran via Gunther Hagleitner)

git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1638694 13f79535-47bb-0310-9956-ffa450edef68