On Thu, 26 Jan 2017 17:10:51 +0900, Katsumi Yamaoka wrote:
> Sorry, that is my fault.  How about this patch?

I'm sorry again.  This is the right one:

* lisp/gnus/gnus-art.el (gnus-article-describe-bindings):
Ignore summary commands that aren't bound to
gnus-article-read-summary-keys keys (bug#18257).