libnss_compat in slackware-current

Although slackware-current has both libnss_compat and libnss_nis, I cannot get + and +@ entries in /etc/passwd to work. Maybe the new, separate libnss_nis does not work together with libnss_compat? But then what is the use of libnss_compat these days? That makes it just another libnss_files. Or is it a bug, and is it supposed to work?

To be clear, if I configure "files nis" for passwd and group in nsswitch.conf, it does work; it is only the more fine-grained "compat" that does not work for me. To such an extent that strace id dvandeun does not show any attempt to open a network connection at all.