I am trying to override default routing by implementing IPartialRouter and the RoutePartial method.  For the most part this works, however if the url that I make the request with matches the CMS hierarchy exactly, the RoutePartial method does not fire.  How do I go about preventing the Optimizely default routing from bypassing my custom router?

public class CustomRouter : IPartialRouter<PageData, PageData>
{
    public PartialRouteData GetPartialVirtualPath(PageData content, UrlGeneratorContext urlGeneratorContext)
    {
        return null;
    }

    public object RoutePartial(PageData content, UrlResolverContext segmentContext)
    {
        // This does not fire when url matches the CMS hierarchy
        // Example:
        //      URL: www.site.com/category/subcategory
        //      CMS: category -> subcategory

        var routedPage = content;
        segmentContext.RemainingSegments = ReadOnlyMemory<char>.Empty;
        segmentContext.Content = routedPage;

        var routeValues = HttpContextFactory.Current.GetRouteData();
        routeValues.Values.Add("test", "test");

        return routedPage;
    }
}