title: Pylint Exception on Win7/Python 3.2: return u''
body: <p>After installing Pylint 1.5.4 on under Windows 7 / Python 3.2.5 (pip install pylint), I get the following exception when trying to invoke:</p>
  
  <pre><code>b:\Sandbox\PyLoad&gt;pylint PyLoad.py
  Traceback (most recent call last):
    File "c:\python32\lib\site-packages\astroid\builder.py", line 172, in _data_build
      node = _parse(data + '\n')
    File "c:\python32\lib\site-packages\astroid\builder.py", line 40, in _parse
      return compile(string, "&lt;string&gt;", 'exec', _ast.PyCF_ONLY_AST)
    File "&lt;string&gt;", line 12
      return u''
               ^
  SyntaxError: invalid syntax
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "c:\python32\lib\runpy.py", line 161, in _run_module_as_main
  "__main__", fname, loader, pkg_name)
    File "c:\python32\lib\runpy.py", line 74, in _run_code
      exec(code, run_globals)
    File "C:\Python32\Scripts\pylint.exe\__main__.py", line 9, in &lt;module&gt;
    File "c:\python32\lib\site-packages\pylint\__init__.py", line 22, in run_pylint
      from pylint.lint import Run
    File "c:\python32\lib\site-packages\pylint\lint.py", line 44, in &lt;module&gt;
      import astroid
    File "c:\python32\lib\site-packages\astroid\__init__.py", line 136, in &lt;module&gt;
      __import__(module[:-3])
    File "c:\python32\lib\site-packages\astroid\brain\brain_builtin_inference.py", line 76, in &lt;module&gt;
      'str': partial(_extend_str, rvalue="''")})
    File "c:\python32\lib\site-packages\astroid\brain\brain_builtin_inference.py", line 72, in extend_builtins
      transform(builtin_ast[class_name])
    File "c:\python32\lib\site-packages\astroid\brain\brain_builtin_inference.py", line 63, in _extend_str
      fake = AstroidBuilder(MANAGER).string_build(code)['whatever']
    File "c:\python32\lib\site-packages\astroid\builder.py", line 146, in string_build
      module = self._data_build(data, modname, path)
    File "c:\python32\lib\site-packages\astroid\builder.py", line 174, in _data_build
      raise exceptions.AstroidBuildingException(exc)
  astroid.exceptions.AstroidBuildingException: invalid syntax (&lt;string&gt;, line 12)
  </code></pre>
  
  <p>It looks like something is trying to return a unicode string using Python 2 syntax, but this is Python 3.</p>
  
  <p>In astroid's builder.py, _data_build is being called with the string:</p>
  
  <pre><code>class whatever(object):
      def join(self, iterable):
          return b''
      def replace(self, old, new, count=None):
          return b''
      def format(self, *args, **kwargs):
          return b''
      def encode(self, encoding='ascii', errors=None):
          return ''
      def decode(self, encoding='ascii', errors=None):
          return u''
             .
             .
             .
  </code></pre>
  
  <p>I assume this <strong>return u''</strong> is causing the problem.</p>
  
  <p>Anyone seen this, and have a solution?</p>