clear fastcgi ctx for internal redirection via named location

src/http/modules/ngx_http_fastcgi_module.c

diff --git a/src/http/modules/ngx_http_fastcgi_module.c b/src/http/modules/ngx_http_fastcgi_module.c
index 88ea672..301449f 100644
--- a/src/http/modules/ngx_http_fastcgi_module.c
+++ b/src/http/modules/ngx_http_fastcgi_module.c
@@ -419,6 +419,8 @@
         return NGX_HTTP_INTERNAL_SERVER_ERROR;
     }
 
+    ngx_http_set_ctx(r, NULL, ngx_http_fastcgi_module);
+
     u = ngx_pcalloc(r->pool, sizeof(ngx_http_upstream_t));
     if (u == NULL) {
         return NGX_HTTP_INTERNAL_SERVER_ERROR;