'Provisional User' example needed to have search permissions added otherwise the sort and group dropdowns were not populated with the names of the properties of the issue. See the thread titled "access control rule for Sort and Group function" by austin.wangxu ending with: https://sourceforge.net/p/roundup/mailman/message/36408780/

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

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

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