# HG changeset patch
# User Igor Sysoev <igor@sysoev.ru>
# Date 1277908768 0
# Node ID a870639d2970fed9bff07a41b93d5ee405970c19
# Parent  8649a0c0f09d5757ef48a8054c611f19f53e76d1
Fix processing
    error_page 502 504 /zero;
    location = /zero { return 204; }

The bug has been introduced in r3634.
The fix also allow to use:
    error_page 502 504 = /zero;
    location = /zero { return 200; }

This case still does not work:
    error_page 502 504 /zero;
    location = /zero { return 200; }

diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -1748,6 +1748,7 @@ ngx_http_send_response(ngx_http_request_
     r->headers_out.status = status;
 
     if (status == NGX_HTTP_NO_CONTENT) {
+        r->header_only = 1;
         return ngx_http_send_header(r);
     }
 
diff --git a/src/http/ngx_http_header_filter_module.c b/src/http/ngx_http_header_filter_module.c
--- a/src/http/ngx_http_header_filter_module.c
+++ b/src/http/ngx_http_header_filter_module.c
@@ -170,6 +170,10 @@ ngx_http_header_filter(ngx_http_request_
 #endif
     u_char                     addr[NGX_SOCKADDR_STRLEN];
 
+    if (r->header_sent) {
+        return NGX_OK;
+    }
+
     r->header_sent = 1;
 
     if (r != r->main) {