RelToSqlConverter should not merge two window functions

@Test void testNestWindow() { 
String query = " SELECT RANK() OVER (ORDER BY \"daily_sales\" DESC) AS \"rank1\" " 
+ "FROM ( SELECT \"product_name\", " 
+ "SUM(\"product_id\") OVER (PARTITION BY \"product_name\") AS \"daily_sales\" "
+ "FROM \"product\" ) subquery"; 

String expected0 = "SELECT RANK() OVER (ORDER BY 2 DESC) AS \"$0\"\n" 
+ "FROM \"foodmart\".\"product\""; 

RuleSet rules = RuleSets.ofList(CoreRules.PROJECT_TO_LOGICAL_PROJECT_AND_WINDOW); 
sql(query).optimize(rules, null) .ok(expected0); 
}

LogicalWindow(window#0=[window(order by [1 DESC] aggs [RANK()])])
  LogicalProject(product_name=[$3], $1=[$15])
    LogicalWindow(window#0=[window(partition {3} aggs [SUM($1)])])
      JdbcTableScan(table=[[foodmart, product]])