DERBY-3155: Add test to verify use of identifiers on the left side of SET clauses in MERGE statements; commit derby-3155-22-ad-testIdentifiersOnLeftSideOfSetClauses.diff.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1566625 13f79535-47bb-0310-9956-ffa450edef68