A few error messages do not supply a value for the format specifier

        raise ConfigurationError('Hostname: %s is not a FQDN')
        raise ConfigurationError('User: %s not found on the system')

What I found really odd was that pylint did not catch these. I checked pylint's capability and it does flag format strings that do not have the correct number of values associated with the format string.

So why didn't pylint find these errors? As far as I can tell the issue is pylint does not know it's string formatting unless you apply the % format operator to the string, otherwise pylint considers it just a string.