diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 7aed84584c..7c417d4e14 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -1013,26 +1013,41 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
 				else
 				{
 					/*
-					 * The tlist of a childless Result could contain
-					 * unresolved ROWID_VAR Vars, in case it's representing a
-					 * target relation which is completely empty because of
-					 * constraint exclusion.  Replace any such Vars by null
-					 * constants, as though they'd been resolved for a leaf
-					 * scan node that doesn't support them.  We could have
-					 * fix_scan_expr do this, but since the case is only
-					 * expected to occur here, it seems safer to special-case
-					 * it here and keep the assertions that ROWID_VARs
-					 * shouldn't be seen by fix_scan_expr.
+					 * The tlist of a dummy Result (one with constant-false
+					 * resconstantqual) could contain Vars, which are
+					 * effectively dangling references and have the potential
+					 * to cause problems in the executor or EXPLAIN.  We could
+					 * not get rid of these earlier without breaking Var
+					 * replacement in upper plan levels, but now let's reduce
+					 * the tlist to a bunch of NULL constants.  Since the
+					 * tlist should never be executed, this has no run-time
+					 * effect.  (One useful side-effect is that this makes it
+					 * safe for fix_scan_expr to assert that it won't see
+					 * ROWID_VARs; without this, unresolved ROWID Vars could
+					 * be found in the tlist of such a result.)
 					 */
-					foreach(l, splan->plan.targetlist)
+					bool		dummy = false;
+
+					if (list_length((List *) splan->resconstantqual) == 1)
 					{
-						TargetEntry *tle = (TargetEntry *) lfirst(l);
-						Var		   *var = (Var *) tle->expr;
+						Const	   *cqual = (Const *) linitial((List *) splan->resconstantqual);
+
+						dummy = IsA(cqual, Const) &&
+							(cqual->constisnull ||
+							 !DatumGetBool(cqual->constvalue));
+					}
 
-						if (var && IsA(var, Var) && var->varno == ROWID_VAR)
-							tle->expr = (Expr *) makeNullConst(var->vartype,
-															   var->vartypmod,
-															   var->varcollid);
+					if (dummy)
+					{
+						foreach(l, splan->plan.targetlist)
+						{
+							TargetEntry *tle = (TargetEntry *) lfirst(l);
+							Node	   *expr = (Node *) tle->expr;
+
+							tle->expr = (Expr *) makeNullConst(exprType(expr),
+															   exprTypmod(expr),
+															   exprCollation(expr));
+						}
 					}
 
 					splan->plan.targetlist =