MIME type "text/html" is already included by default

See http://nginx.org/en/docs/http/ngx_http_gzip_module.html#gzip_types

scripts/config/templates/nginx.conf.erb

@@ -11,7 +11,7 @@ http {
   gzip on;
   gzip_comp_level 6;
   gzip_min_length 512;
-  gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript text/html;
+  gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;
   gzip_vary on;
   gzip_proxied any;