XHTMLSerializer broken with preamble

[jruigrok]

Using r785 with some of my own code (and apparently Trac 0.11b1 yields the same issue) gives:

Traceback (most recent call last):
  File "/usr/local/lib/python2.5/site-packages/CherryPy-3.0.2-py2.5.egg/cherrypy/_cprequest.py", line 551, in respond
    cherrypy.response.body = self.handler()
  File "/usr/local/lib/python2.5/site-packages/CherryPy-3.0.2-py2.5.egg/cherrypy/_cpdispatch.py", line 24, in __call__
    return self.callable(*self.args, **self.kwargs)
  File "/usr/home/asmodai/www/kouyou/home/controller.py", line 13, in index
    return stream.render('xhtml', doctype=DocType.XHTML_STRICT)
  File "build/bdist.freebsd-6.3-PRERELEASE-i386/egg/genshi/core.py", line 172, in render
    return encode(generator, method=method, encoding=encoding)
  File "build/bdist.freebsd-6.3-PRERELEASE-i386/egg/genshi/output.py", line 45, in encode
    output = u''.join(list(iterator))
  File "build/bdist.freebsd-6.3-PRERELEASE-i386/egg/genshi/output.py", line 287, in __call__
    stream = chain(self.preamble, stream)
AttributeError: 'XHTMLSerializer' object has no attribute 'preamble'

So it seems XHTML serialization is broken.

[athomas]

My fault. Accidentally committed a patch from #156. Fixed in r785/r786.