Proposed fix for the row-value TRIGGER UPDATE problem described in 
ticket [8c9458e7].

FossilOrigin-Name: 61a442ea2ceec2cbd327dae0ff5214e1f3c69ec0
diff --git a/src/expr.c b/src/expr.c
index b23f179..ebc9ca6 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -1088,7 +1088,7 @@
   assert( flags==EXPRDUP_REDUCE || flags==0 ); /* Only one flag value allowed */
   assert( EXPR_FULLSIZE<=0xfff );
   assert( (0xfff & (EP_Reduced|EP_TokenOnly))==0 );
-  if( 0==flags ){
+  if( 0==flags || p->op==TK_SELECT_COLUMN ){
     nSize = EXPR_FULLSIZE;
   }else{
     assert( !ExprHasProperty(p, EP_TokenOnly|EP_Reduced) );
@@ -1231,6 +1231,8 @@
       if( !ExprHasProperty(p, EP_TokenOnly|EP_Leaf) ){
         if( pNew->op==TK_SELECT_COLUMN ){
           pNew->pLeft = p->pLeft;
+          assert( p->iColumn==0 || p->pRight==0 );
+          assert( p->pRight==0  || p->pRight==p->pLeft );
         }else{
           pNew->pLeft = sqlite3ExprDup(db, p->pLeft, 0);
         }
@@ -1307,7 +1309,20 @@
   pOldItem = p->a;
   for(i=0; i<p->nExpr; i++, pItem++, pOldItem++){
     Expr *pOldExpr = pOldItem->pExpr;
+    Expr *pNewExpr;
     pItem->pExpr = sqlite3ExprDup(db, pOldExpr, flags);
+    if( pOldExpr 
+     && pOldExpr->op==TK_SELECT_COLUMN
+     && (pNewExpr = pItem->pExpr)!=0 
+    ){
+      assert( pNewExpr->iColumn==0 || i>0 );
+      if( pNewExpr->iColumn==0 ){
+        assert( pOldExpr->pLeft==pOldExpr->pRight );
+        pNewExpr->pLeft = pNewExpr->pRight;
+      }else if( pItem[-1].pExpr!=0 ){
+        pNewExpr->pLeft = pItem[-1].pExpr->pLeft;
+      }
+    }
     pItem->zName = sqlite3DbStrDup(db, pOldItem->zName);
     pItem->zSpan = sqlite3DbStrDup(db, pOldItem->zSpan);
     pItem->sortOrder = pOldItem->sortOrder;