add body.close check for HEAD requests

lib/application.js

@@ -210,7 +210,12 @@ function *respond(next){
   // Stream body
   if (body instanceof Stream) {
     if (!~body.listeners('error').indexOf(this.onerror)) body.on('error', this.onerror);
-    if (head) return body.close(), res.end();
+   
+    if (head) {
+      if (body.close) body.close();
+      return res.end();
+    }
+   
     return body.pipe(res);
   }