7.3.: Notice messages with Log4php

Lots of E_NOTICE messages for the logger. They seem to be related to the same 2 lines of code:

Notice:  Only variable references should be returned by reference in /var/www/html/vt730/libraries/log4php.debug/LoggerAppender.php on line 73

and

Notice:  Only variable references should be returned by reference in /var/www/html/vt730/libraries/log4php.debug/LoggerPropertyConfigurator.php on line 565