[PATCH 3 of 5] Fixed Upgrade header clearing with proxy_cache

[Maxim Dounin]

# HG changeset patch
# User Maxim Dounin <mdounin at mdounin.ru>
# Date 1320965914 -10800
# Node ID a0e9e95fbbf7913506f455669217f87c1b8da2de
# Parent  de56bca2d2e849444f52655c87b2e99c10c42f4a
Fixed Upgrade header clearing with proxy_cache.

This was missed in proxy HTTP/1.1 support commit (r4127).

diff --git a/src/http/modules/ngx_http_proxy_module.c b/src/http/modules/ngx_http_proxy_module.c
--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -543,6 +543,7 @@ static ngx_keyval_t  ngx_http_proxy_cach
     { ngx_string("Connection"), ngx_string("close") },
     { ngx_string("Keep-Alive"), ngx_string("") },
     { ngx_string("Expect"), ngx_string("") },
+    { ngx_string("Upgrade"), ngx_string("") },
     { ngx_string("If-Modified-Since"), ngx_string("") },
     { ngx_string("If-Unmodified-Since"), ngx_string("") },
     { ngx_string("If-None-Match"), ngx_string("") },