What does #(nop) mean in docker history?
<p>What does the <code>#(nop)</code> prefix mean when listing <code>docker history</code>?</p>

<pre><code>$ docker history swarm
IMAGE               CREATED             CREATED BY   
c54bba046158        9 days ago          /bin/sh -c #(nop) CMD ["--help"]
</code></pre>