FAI does not return with the appropriate status code in all cases, example:

[...]
/var/log/fai/grml/last/shell.log:dpkg: error processing groff-base (--purge):
/var/log/fai/grml/last/shell.log:Errors were encountered while processing:
/var/log/fai/grml/last/shell.log:dpkg: error processing locales (--purge):
/var/log/fai/grml/last/shell.log:Errors were encountered while processing:
/var/log/fai/grml/last/variables.log:STOP_ON_ERROR=99999
/var/log/fai/grml/last/variables.log:task_error=0
/var/log/fai/grml/last/variables.log:task_error_func=