commit 8ce360e21d972879e0fc29565c6343a100d507fe
Author: weiyue <weiyue@taobao.com>
Date:   Thu Jan 7 12:13:41 2016 +0800

    support 'proxy_http_version auto;'

diff --git a/src/http/modules/ngx_http_proxy_module.c b/src/http/modules/ngx_http_proxy_module.c
index 1a837ae..7835327 100644
--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -228,6 +228,7 @@ static ngx_conf_bitmask_t  ngx_http_proxy_ssl_protocols[] = {
 static ngx_conf_enum_t  ngx_http_proxy_http_version[] = {
     { ngx_string("1.0"), NGX_HTTP_VERSION_10 },
     { ngx_string("1.1"), NGX_HTTP_VERSION_11 },
+    { ngx_string("auto"), 0 },
     { ngx_null_string, 0 }
 };
 
@@ -1224,9 +1225,19 @@ ngx_http_proxy_create_request(ngx_http_request_t *r)
         b->last = ngx_cpymem(b->last, ngx_http_proxy_version_11,
                              sizeof(ngx_http_proxy_version_11) - 1);
 
-    } else {
+    } else if (plcf->http_version == NGX_HTTP_VERSION_10) {
         b->last = ngx_cpymem(b->last, ngx_http_proxy_version,
                              sizeof(ngx_http_proxy_version) - 1);
+
+    } else {
+        if (r->http_version == NGX_HTTP_VERSION_11) {
+            b->last = ngx_cpymem(b->last, ngx_http_proxy_version_11,
+                                 sizeof(ngx_http_proxy_version_11) - 1);
+
+        } else {
+            b->last = ngx_cpymem(b->last, ngx_http_proxy_version,
+                                 sizeof(ngx_http_proxy_version) - 1);
+        }
     }
 
     ngx_memzero(&e, sizeof(ngx_http_script_engine_t));
diff --git a/tests/nginx-tests/cases/proxy_http_version_auto.t b/tests/nginx-tests/cases/proxy_http_version_auto.t
new file mode 100644
index 0000000..061e7dc
--- /dev/null
+++ b/tests/nginx-tests/cases/proxy_http_version_auto.t
@@ -0,0 +1,70 @@
+#!/usr/bin/perl
+
+
+###############################################################################
+
+use warnings;
+use strict;
+
+use Test::More;
+
+BEGIN { use FindBin; chdir($FindBin::Bin); }
+
+use Socket qw/ CRLF /;
+
+use lib 'lib';
+use Test::Nginx;
+
+###############################################################################
+
+select STDERR; $| = 1;
+select STDOUT; $| = 1;
+
+my $t = Test::Nginx->new()->plan(2);
+$t->write_file_expand('nginx.conf', <<'EOF');
+
+%%TEST_GLOBALS%%
+
+daemon         off;
+
+%%TEST_GLOBALS_DSO%%
+
+events {
+}
+
+http {
+    %%TEST_GLOBALS_HTTP%%
+
+    proxy_http_version auto;
+
+    server {
+        listen       127.0.0.1:8080;
+        server_name  localhost;
+
+        location / {
+            proxy_pass http://127.0.0.1:1970;
+        }
+    }
+
+    server {
+        listen       127.0.0.1:1970;
+        server_name  localhost;
+
+        location / {
+            echo "$request";
+        }
+    }
+
+}
+
+EOF
+
+
+$t->run();
+
+###############################################################################
+
+like(http('GET / HTTP/1.1' . CRLF . 'Host: localhost' . CRLF . 'Connection:close'.  CRLF . CRLF), qr!GET / HTTP/1.1!, 'http 1.1');
+like(http('GET / HTTP/1.0' . CRLF . 'Host: localhost' . CRLF . 'Connection:close'.  CRLF . CRLF), qr!GET / HTTP/1.0!, 'http 1.0');
+
+###############################################################################