title: Memcached::touchByKey(): touch is only supported with binary protocol
body: <p>I'm trying to use TouchByKey which is a memcached function but this warning pops up:</p>
  
  <p><code>Memcached::touchByKey(): touch is only supported with binary protocol</code></p>
  
  <p>I found that I could use something like:<code>$mc-&gt;setOption(\Memcached::OPT_BINARY_PROTOCOL, true);</code> on the client side.</p>
  
  <p>The same problem happens with <code>Touch()</code></p>
  
  <p>My question is, do I need to change anything on the memcache server itself? Why is this even requiring Binary protocol? Why isn't this functionality available for the current ASCII protocol? </p>