ContainerException when a post is performed from a site's homepage

Under the following circumstances we get a container exception reading "Can only redirect to a context relative path starting with a '/'.". And a 500 error of course.

• Have showContextPath=false in your mount properties
• Use a component in your homepage that posts to <hst:actionURL />. I used the poll component
• perform a post request

The post maybe successful, but the redirection fails with the container exception. Responsible for this is the check in org.hippoecm.hst.core.container.ActionValve, line 156. When we post from the home location, having showContextPath=false, the contextPath of the redirection url is empty and ActionValve throws the exception.