I've tried all the way back to 3.3.16 when I first reported it. The following fails to work correctly.
php_admin_value open_basedir /usr/share/pear:/www/$VH_ROOT:/tmp
php_admin_value error_log /www/$VH_ROOT/logs/php_errors.log
However, if I replace $VH_ROOT with $VH_NAME it seems fine.
The value of $VH_ROOT would be for example: /www/home.com