fix stream leak on HEAD. Closes #91

lib/application.js

@@ -178,7 +178,7 @@ function *respond(next){
   // Stream body
   if (body instanceof Stream) {
     if (!~body.listeners('error').indexOf(this.onerror)) body.on('error', this.onerror);
-    if (head) return res.end();
+    if (head) return body.close(), res.end();
     return body.pipe(res);
   }