issue2550749 - the xmlrpc interface is invoked on content type and not url path. Sending any text/xml data to roundup results in invoking the xml-rpc interface, but a REST or other interface could also consume xml data and do something different. So require the use of 'http(s)://.../xmlrpc' uri to trigger the xmlrpc interface.

def init_severity(db, cl, nodeid, newvalues):
    """Make sure severity is set on new issues"""
    if newvalues.has_key('severity') and newvalues['severity']:
        return

    normal = db.severity.lookup('normal')
    newvalues['severity'] = normal

def init(db):
    db.issue.audit('create', init_severity)