duplicate Vary: Accept-Encoding header

[philipp]

I use nginx 1.4.1 with gunzip = on and gzip_vary = on. This leads to a
duplicate Vary Header.

gzip_vary should do nothing if the header is already present:

user at aladin:~$ curl -I -A test http://192.168.56.249/
HTTP/1.1 302 Found
Server: nginx
Date: Tue, 25 Jun 2013 06:45:12 GMT
Content-Type: text/html
Connection: keep-alive
Vary: Accept-Encoding
Location: index.htm
Vary: Accept-Encoding

I have no control of the upstream server maybe it sends a Vary header or
not, in order to be safe I would like to use gzip_vary = on in order to
prevent any problems here.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,240322,240322#msg-240322