Backport [3.0.1]Redirects from non root HstComponents are broken

Reproduction:

In archetype created project, create an HstComponent

package org.onehippo.cms7.hst.beans;

import java.io.IOException;

import org.hippoecm.hst.component.support.bean.BaseHstComponent;
import org.hippoecm.hst.core.component.HstComponentException;
import org.hippoecm.hst.core.component.HstRequest;
import org.hippoecm.hst.core.component.HstResponse;

public class RedirectComponent extends BaseHstComponent {

@Override
public void doBeforeRender(final HstRequest request, final HstResponse response) throws HstComponentException {
try

catch (IOException e)

return;
}
}

then, on a child component, say http://localhost:8080/cms/console/?1&path=/hst:hst/hst:configurations/gettingstarted/hst:pages/homepage/main

set

hst:componentclassname = org.onehippo.cms7.hst.beans.RedirectComponent

Result is :

[INFO] [talledLocalContainer] 23.09.2015 17:15:20 WARN http-nio-8080-exec-1 [AggregationValve.invoke:225] Exception during sendRedirect. java.lang.IllegalStateException: Cannot call sendRedirect() after the response has been committed