title: Default int value with xmlrpclib
body: <p>I tried to execute the following code, but <code>xmlrpclib</code> is raising an exception:</p>
  
  <pre><code>&gt;&gt;&gt; import xmlrpclib
  &gt;&gt;&gt; data = """&lt;?xml version="1.0"?&gt; 
  ... &lt;methodCall&gt;
  ...     &lt;methodName&gt;test_method&lt;/methodName&gt;
  ...     &lt;params&gt;
  ...         &lt;param&gt;
  ...             &lt;value&gt;
  ...                 &lt;int/&gt;
  ...             &lt;/value&gt;
  ...         &lt;/param&gt;
  ...     &lt;/params&gt;
  ... &lt;/methodCall&gt;"""
  &gt;&gt;&gt; xmlrpclib.loads(data)
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "/usr/lib64/python2.7/xmlrpclib.py", line 1141, in loads
      p.feed(data)
    File "/usr/lib64/python2.7/xmlrpclib.py", line 558, in feed
      self._parser.Parse(data, 0)
    File "/usr/lib64/python2.7/xmlrpclib.py", line 829, in end
      return f(self, join(self._data, ""))
    File "/usr/lib64/python2.7/xmlrpclib.py", line 864, in end_int
      self.append(int(data))
  ValueError: invalid literal for int() with base 10: ''
  </code></pre>
  
  <p>If I replace <code>&lt;int/&gt;</code> by <code>&lt;int&gt;&lt;/int&gt;</code>, the error is the same; but with <code>&lt;int&gt;0&lt;/int&gt;</code> no exception is raised. Same results in python3 with <code>xmlrpc.client</code>.</p>
  
  <p>I tried to do the same thing with <a href="http://php.net/manual/fr/book.xmlrpc.php" rel="nofollow">PHP</a>, and it worked without any trouble:</p>
  
  <pre><code>php &gt; $data = '&lt;?xml version="1.0"?&gt;&lt;methodCall&gt;&lt;methodName&gt;test_method&lt;/methodName&gt;&lt;params&gt;&lt;param&gt;&lt;value&gt;&lt;int/&gt;&lt;/value&gt;&lt;/param&gt;&lt;/params&gt;&lt;/methodCall&gt;';
  php &gt; print_r(xmlrpc_decode($data));
  Array
  (
      [0] =&gt; 0
  )
  </code></pre>
  
  <p>The <a href="http://xml-rpc.net/faq/xmlrpcnetfaq-2-5-0.html" rel="nofollow">documentation</a> from the .NET implementation also implies that <code>&lt;int/&gt;</code> would be translated to 0:</p>
  
  <blockquote>
    <p>If an XML-RPC struct member is missing its corresponding .NET struct member will be set to null instead of the default value for the type if a non-nullable type had been used, for example null instead of zero for an integer.</p>
  </blockquote>
  
  <p>Is this behaviour a bug from the Python implementation?</p>