PIG-3492: ColumnPrune dropping used column due to LogicalRelationalOperator.fixDuplicateUids changes not propagating

git-svn-id: https://svn.apache.org/repos/asf/pig/branches/branch-0.12@1535089 13f79535-47bb-0310-9956-ffa450edef68
PIG-3530: Some e2e tests is broken due to PIG-3480

git-svn-id: https://svn.apache.org/repos/asf/pig/branches/branch-0.12@1535097 13f79535-47bb-0310-9956-ffa450edef68