title: XML XPath search with Python lxml fails to filter on text() output
body: <p>Probably missing something obvious - when I filter for general "a" nodes, I get to see their text - including the target link I want - just fine:</p>
  
  <pre><code>ipdb&gt; print [x.text for x in root.xpath(u".//a")]
  [u'\u0391\u03c0\u03bf\u03c3\u03cd\u03bd\u03b4\u03b5\u03c3\u03b7', None, ... ]
  </code></pre>
  
  <p>But when I filter for the specific text contained in the first 'a' element returned above, I get nothing:</p>
  
  <pre><code>ipdb&gt; print [x.text for x in root.xpath(
      u".//a[text()=" + 
      u'\u0391\u03c0\u03bf\u03c3\u03cd\u03bd\u03b4\u03b5\u03c3\u03b7' + 
      u']'  )]
  []
  ipdb&gt; 
  </code></pre>
  
  <p>Any ideas?</p>