Upstream: keep request body file from removal if requested. The new request flag "preserve_body" indicates that the request body file should not be removed by the upstream module because it may be used later by a subrequest. The flag is set by the SSI (ticket #585), addition and slice modules. Additionally, it is also set by the upstream module when a background cache update subrequest is started to prevent the request body file removal after an internal redirect. Only the main request is now allowed to remove the file.

--- a/src/http/modules/ngx_http_ssi_filter_module.c
+++ b/src/http/modules/ngx_http_ssi_filter_module.c
@@ -370,6 +370,8 @@ ngx_http_ssi_header_filter(ngx_http_requ
         ngx_http_clear_content_length(r);
         ngx_http_clear_accept_ranges(r);
 
+        r->preserve_body = 1;
+
         if (!slcf->last_modified) {
             ngx_http_clear_last_modified(r);
             ngx_http_clear_etag(r);