Make HTMLClass::history signature compatible to _HTMLItem::history _HTMLItem::history accepts 4 optional named parameters. If a template (e.g. issue.item.html) calls history with a named param and then is called in the context of creating a new issue, you get a traceback. Change HTMLClass::history to accept any named parameter so adding new named params to _HTMLItem::history doesn't require a change to HTMLClass::history.

try:
    # Python 3+.
    from xmlrpc import client, server
    server.SimpleXMLRPCDispatcher
except (ImportError, AttributeError):
    # Python 2.
    import xmlrpclib as client  # noqa: F401
    import SimpleXMLRPCServer as server