fix the previous commit

src/http/ngx_http_special_response.c

diff --git a/src/http/ngx_http_special_response.c b/src/http/ngx_http_special_response.c
index 9bf9916..9765430 100644
--- a/src/http/ngx_http_special_response.c
+++ b/src/http/ngx_http_special_response.c
@@ -454,6 +454,8 @@
 
     ngx_http_clean_header(r);
 
+    ctx = NULL;
+
     if (m) {
         ctx = r->ctx[m->ctx_index];
     }