Do this only when the entire request body is empty and
r->request_body_in_file_only is set.
The issue manifested itself with missing warning "a client request body is
buffered to a temporary file" when the entire rb->buf is full and all buffers
are delayed by a filter.
if (rb->rest > 0) {
- if (rb->buf && rb->buf->last == rb->buf->end
+ if (rb->bufs && rb->buf && rb->buf->last == rb->buf->end
&& ngx_http_write_request_body(r) != NGX_OK)
{
return NGX_HTTP_INTERNAL_SERVER_ERROR;