How to set HttpResponse StatusDescription in a content handler?

Question

I am trying to set a custom HTTP status header in an HTTP response. E.g.:

400 Why do you want to do that

I am doing this by setting the StatusDescription of an HttpResponse in an IHttpHandler, in

<%@ WebHandler Language="C#" Class="Foo" %>

using System;
using System.Web;

public class Foo : IHttpHandler
{

    public void ProcessRequest(HttpContext context)
    {
        context.Response.StatusCode = (int)System.Net.HttpStatusCode.BadRequest;
        context.Response.StatusDescription = "Why do you want to do that";

            //Unnecessary; the string already contains this
        context.Response.Status = "400 Why do you want to do that";

        context.Response.ContentType = "text/plain";
        context.Response.Write("Hello World");
    }

    public bool IsReusable { get { return false; } }
}

But in the response headers from the server the status line doesn't contain what i told it to contain, and instead continues to contain the default StatusDescription:

400 Bad Request

How do change the StatusDescription of an HttpResponse header when in a generic handler?

Bonus Chatter

There are three properties:

• int StatusCode: 400
• String StatusDescription: Bad Request
• String Status: 400 Bad Request

Setting the StatusCode will alter the StatusDescription and Status

                    StatuCode  StatusDescription  Status              
==================  =========  =================  ====================
initial             200        OK                 200 OK
StatusCode=400;
                    400        Bad Request        400 Bad Request
StatusDescription = "Too much want";
                    400        Too much want      400 Too much want

It also works the other way:

                    StatuCode  StatusDescription  Status              
==================  =========  =================  ====================
initial             200        OK                 200 OK
StatusDescription="Brilliant";
                    200        Brilliant          200 Brilliant
StatusCode=451;
                    451        Brilliant          451 Brilliant

and the other way

                    StatuCode  StatusDescription  Status              
==================  =========  =================  ====================
initial             200        OK                 200 OK
Status="451 Brilliant"
                    451        Brilliant          451 Brilliant

Bonus Bonus Chatter

From RFC 2616 - Hypertext Transfer Protocol -- HTTP/1.1:

6.1.1 Status Code and Reason Phrase

The individual values of the numeric status codes defined for HTTP/1.1, and an example set of corresponding Reason-Phrase's, are presented below. The reason phrases listed here are only recommendations -- they MAY be replaced by local equivalents without affecting the protocol.