do not discard body if it has been already read

src/http/ngx_http_request_body.c

diff --git a/src/http/ngx_http_request_body.c b/src/http/ngx_http_request_body.c
index dfe5e0f..a9583c7 100644
--- a/src/http/ngx_http_request_body.c
+++ b/src/http/ngx_http_request_body.c
@@ -442,7 +442,7 @@
         ngx_del_timer(rev);
     }
 
-    if (r->headers_in.content_length_n <= 0) {
+    if (r->headers_in.content_length_n <= 0 || r->request_body) {
         return NGX_OK;
     }