title: xmllint failing to properly query with xpath
body: <p>I'm trying to query an xml file generated by adium. xmlwf says that it's well formed. By using xmllint's debug option i get the following:</p>
  
  <pre><code>$ xmllint --debug doc.xml
  DOCUMENT
  version=1.0
  encoding=UTF-8
  URL=doc.xml
  standalone=true
    ELEMENT chat
      default namespace href=http://purl.org/net/ulf/ns/0.4-02
      ATTRIBUTE account
        TEXT
          content=foo@bar.com
      ATTRIBUTE service
        TEXT compact
          content=MSN
      TEXT compact
        content= 
      ELEMENT event
        ATTRIBUTE type
  </code></pre>
  
  <p>Everything seems to parse just fine. However, when I try to query even the simplest things, I don't get anything:</p>
  
  <pre><code>$ xmllint --xpath '/chat' doc.xml 
  XPath set is empty
  </code></pre>
  
  <p>What's happening? Running that exact same query using xpath returns the correct results (however with no newline between results). Am I doing something wrong or is xmllint just not working properly?</p>
  
  <p>Here's a shorter, anonymized version of the xml that shows the same behavior:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8" ?&gt;
  &lt;chat xmlns="http://purl.org/net/ulf/ns/0.4-02" account="foo@bar.com" service="MSN"&gt;
  &lt;event type="windowOpened" sender="foo@bar.com" time="2011-11-22T00:34:43-03:00"&gt;&lt;/event&gt;
  &lt;message sender="foo@bar.com" time="2011-11-22T00:34:43-03:00" alias="foo"&gt;&lt;div&gt;&lt;span style="color: #000000; font-family: Helvetica; font-size: 12pt;"&gt;hi&lt;/span&gt;&lt;/div&gt;&lt;/message&gt;
  &lt;/chat&gt;
  </code></pre>