fix segfault if 400 or 414 errors are handled intricately

src/http/ngx_http_request.c

diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
index a1e02ac..4cd1d8f 100644
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -384,6 +384,7 @@
     r->loc_conf = cscf->ctx->loc_conf;
 
     rev->handler = ngx_http_process_request_line;
+    r->read_event_handler = ngx_http_block_reading;
 
 #if (NGX_HTTP_SSL)