Python exception when associating an openid account with a dev.launchpad.net one

Per RT#39410, Loic Minier got a pything exception when logging into dev.launchpad.net for the first time:

While trying to login to dev.launchpad.net today, presumably
associating my openid with dev.launchpad.net for the first time ever, I
got a python traceback after submitting my password for confirmation:
TypeError
__init__() takes exactly 2 arguments (1 given)

/var/lib/python-support/python2.5/MoinMoin/request/request_fcgi.py in __init__ (self=<MoinMoin.request.request_fcgi.Request object at 0x1555850>, fcgRequest=<MoinMoin.support.thfcgi.Request instance at 0x1542f80>, env={'CONTENT_LENGTH': '98', 'CONTENT_TYPE': 'application/x-www-form-urlencoded', 'DOCUMENT_ROOT': '/srv/dev.launchpad.net/www/htdocs/', 'GATEWAY_INTERFACE': 'CGI/1.1', 'HTTP_ACCEPT': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8', 'HTTP_ACCEPT_CHARSET': 'ISO-8859-1,utf-8;q=0.7,*;q=0.7', 'HTTP_ACCEPT_ENCODING': 'gzip,deflate', 'HTTP_ACCEPT_LANGUAGE': 'en-us,en;q=0.8,fr;q=0.5,fr-fr;q=0.3', 'HTTP_CACHE_CONTROL': 'max-age=259200', 'HTTP_CONNECTION': 'keep-alive', ...}, form=FieldStorage(None, None, [MiniFieldStorage('logi...niFieldStorage('submit', 'Associate this name')]), properties={'script_name': '/'})

26 self.fcgform = form
27 self._setup_vars_from_std_env(env)
28 RequestBase.__init__(self, properties)
29
30 except Exception, err: global RequestBase = <class 'MoinMoin.request.RequestBase'>, RequestBase.__init__ = <unbound method RequestBase.__init__>, self = <MoinMoin.request.request_fcgi.Request object at 0x1555850>, properties = {'script_name': '/'}

/var/lib/python-support/python2.5/MoinMoin/request/__init__.py in __init__ (self=<MoinMoin.request.request_fcgi.Request object at 0x1555850>, properties={'script_name': '/'})
[...]