Opera和RCurl中的HTTP 404，但Firefox中没有

Question

我在向localhost上的Web服务发送请求时收到HTTP 404：

http://localhost/my-ws/Test

在Firefox中我收到HTTP 200 OK：

GET /my-ws/Test HTTP/1.1
Host: localhost
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20100101 Firefox/13.0.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: de-de,de;q=0.8,en-us;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Connection: keep-alive
Cache-Control: max-age=0

在Opera中：

GET /my-ws/Test HTTP/1.1 
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; en; rv:2.0) Gecko/20100101 Firefox/4.0 Opera 12.00
Host:   localhost
Accept: text/html, application/xml;q=0.9, application/xhtml+xml, image/png, image/webp, image/jpeg, image/gif, image/x-xbitmap, */*;q=0.1
Accept-Language:    en,de-DE;q=0.9,de;q=0.8
Accept-Encoding:    gzip, deflate
Pragma: no-cache
Cache-Control:  no-cache
Connection: Keep-Alive

这里有什么问题？要为RCurl提供哪些参数以获得与Firefox相同的结果？