Upstream: disable body cleanup with preserve_output (ticket #1565).

With u->conf->preserve_output set the request body file might be used
after the response header is sent, so avoid cleaning it.  (Normally
this is not a problem as u->conf->preserve_output is only set with
r->request_body_no_buffering, but the request body might be already
written to a file in a different context.)

src/http/ngx_http_upstream.c

diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index 8fc3042..47cc6cc 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -2901,7 +2901,8 @@
     }
 
     if (r->request_body && r->request_body->temp_file
-        && r == r->main && !r->preserve_body)
+        && r == r->main && !r->preserve_body
+        && !u->conf->preserve_output)
     {
         ngx_pool_run_cleanup_file(r->pool, r->request_body->temp_file->file.fd);
         r->request_body->temp_file->file.fd = NGX_INVALID_FILE;