title: xml.etree.ElementTree findall() not behaving as expected
body: <pre><code>&gt;&gt;&gt; import xml.etree.ElementTree as ET
  &gt;&gt;&gt; t = ET.fromstring('&lt;root&gt;&lt;field name="tcp.option_len" &gt;&lt;/field&gt;&lt;/root&gt;')
  &gt;&gt;&gt; t.findall('.//field [@name="tcp.option_len"]')
  []
  </code></pre>
  
  <p>Why isn't the <code>field</code> returned?</p>