asp.net RewritePath重定向HTTP头Content-Location暴露真实路径解决方法

asp.net使用rewritepath重定向后，服务器响应的http头会多个content-location：

http/1.1 200 ok
content-length: 48150
content-type: image/jpeg
content-location: http://www.mzwu.com/test.jpg
last-modified: tue, 18 dec 2012 15:01:50 gmt
accept-ranges: bytes
etag: "e119ee9b30ddcd1:1c48"
server: microsoft-iis/6.0
x-powered-by: asp.net
date: mon, 08 sep 2014 01:29:40 gmt

content-location值为重定向文件的真实路径，在一些场合下我们不想让客户端知道这个路径，有办法去掉它吗？去不掉，但可以手工在iis中给网站设置一个同名http头借以隐藏真实路径：

现在效果如下

http/1.1 200 ok
content-length: 48150
content-type: image/jpeg
content-location: mzwu.com
last-modified: tue, 18 dec 2012 15:01:50 gmt
accept-ranges: bytes
etag: "e119ee9b30ddcd1:1c58"
server: microsoft-iis/6.0
x-powered-by: asp.net
date: mon, 08 sep 2014 01:42:50 gmt