title: Sites not accepting wget user agent header
body: <p>When I run this command:</p>
  
  <pre><code>wget --user-agent="Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:21.0) Gecko/20100101 Firefox/21.0"  http://yahoo.com
  </code></pre>
  
  <p>...I get this result (with nothing else in the file):</p>
  
  <pre><code>&lt;!-- hw147.fp.gq1.yahoo.com uncompressed/chunked Wed Jun 19 03:42:44 UTC 2013 --&gt;
  </code></pre>
  
  <p>But when I run <code>wget http://yahoo.com</code> with no <code>--user-agent</code> option, I get the full page.</p>
  
  <p>The user agent is the same header that my current browser sends. Why does this happen? Is there a way to make sure the user agent doesn't get blocked when using wget?</p>