'fai -vNu diskless dirinstall' does not use the hostname/class 'diskless'

[Andreas B. Mundt]

Hello everybody,

bringing debian-lan up-to-date for stretch, I run into a bug/problem.
A dirinstall with the command:

       fai -vNu diskless dirinstall $DLROOT

ends up using not the class 'diskless' but the hostname of the
faiserver, in my case 'mainserver':

root at mainserver:~# cat /var/log/fai/diskless/last-dirinstall/FAI_CLASSES
DEFAULT
LINUX
AMD64
DEBIAN
LVM5_A
CUPS_CLIENT
LOG_CLIENT
LDAP_CLIENT
NFS_CLIENT
KERBEROS_CLIENT
CLIENT_A
XORG
DISKLESS_CLIENT
mainserver          ←
LAST

It looks as for some reason the option '-u' does not work properly.
Any ideas?

Best regards,

     Andi