Yast2 user administration: umask for home dir

Hello,
I changed the umask in Yast’s useradmin-tool to 077 to prevent access of new users to other home directories.
When I updated the kiwi-ltsp packages the thinclients didn’t start anymore. The permissions for new files and directories in /srv/tftpboot/* were too restrictive.
Is the description in Yast wrong? (“umask for home directories”)
Or is it a bug?