Fix test failure caused by making genconfig trackerless When I removed the need to have a tracker for genconfig, I broke a couple of tests. The breakage was hidden by a bad workflow. This change allows the tests to pass and refactors reporting of UsageError exceptions in admin.py. It also adds a test for failure in install command as there is a test case for it and this test tests the refactor.

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)