Steps to Reproduce

1. run attached zhtml page with initiator

   public class RedirectInit implements Initiator {
   
   	@Override
   	public void doInit(Page page, Map<String, Object> args) throws Exception {
   		
   		Executions.sendRedirect("target.zul");
   	}
   }
   

   web.xml

   	<servlet>
   		<description>ZK loader for ZUML pages</description>
   		<servlet-name>zkLoader</servlet-name>
   		<servlet-class>org.zkoss.zk.ui.http.DHtmlLayoutServlet</servlet-class>
   		<init-param>
   			<param-name>update-uri</param-name>
   			<param-value>/zkau</param-value>
   		</init-param>
   
   		<load-on-startup>1</load-on-startup>
   	</servlet>
   	<servlet-mapping>
   		<servlet-name>zkLoader</servlet-name>
   		<url-pattern>*.zhtml</url-pattern>
   	</servlet-mapping>
   

2. visit the zhtml page

Actual Result

The browser is not redirected to the target page.

Debug Information

5.0.0 and 5.0.1 doesn't have this issue.
Since 5.0.2 has the issue.
Initiator works correctly on a zul page.