The man page for smbumount contains this text: "The normal umount program works perfectly well, but it would certainly be problematic to make umount setuid root." umount -is- setuid root. So that non-root users can umount their "user" shares, y'know? Reproducible: Always Steps to Reproduce: 1. man smbumount Actual Results: Received a peculiar statement about /bin/umount. Expected Results: Truthful information.
You need to complain upstream - https://bugzilla.samba.org/
Will do.