HTCONDOR-638 Fix crash when authentication is disabled
HTCONDOR-638 Fix crash when authentication is disabled

When authentication is disabled (i.e. only peer IP address is used for
authorization), there's no authentication method to examine. We already
reject if authentication is required but wasn't performed.

htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor