1148919 - 148915 - remove traceback from log if user enters incorrect password

By logging an error rather than an exception, the traceback is left out of the logs. Fixes [BZ-1148919](https://bugzilla.redhat.com/show_bug.cgi?id=1148919) and [BZ-1148915](https://bugzilla.redhat.com/show_bug.cgi?id=1148915)
Is _log_client_exception part of the superclass? If not, can we remove it now? If so, I imagine other things are still using it.