Slackware current - mount works, umount does not for non-root user

I have a several boxes that I'm testing Slackware current on. So far it's working quite well, I even installed the Mate desktop on one, which is also working well.

However - I found one change from Slackware 14.2. I allow non-root users to mount and umount certain shares, and I reference these shares in fstab so the non-root users can do this. It's been working fine for a very long time. The entries in fstab that let this happen have not changed in a few years.

With slackware current, mounting works, but when they umount, they get this:

umount: <mount point>: umount failed: Operation not permitted.

These shares are hosted on windows servers. If I do this with a share hosted on another linux box via smaba, it works fine. I also tried different windows shares - none of them can be umounted by the non-root user.

I have duplicated this on more than one box running Slackware current. A quick romp through Google reveals nothing.

Summary:
Non-root user cannot umount their own shares on Slackware current
fstab lines that make this work have not changed in years.
This works on Slackware 14.2
This does not work on Slackware current
This works with samba shares on linux boxes, does not work with shares on windows server

PS: One slackware-current box is using the 4.19.3 kernel. Another is using 4.20.2 kernel. Not sure that makes any difference.

Being lazy, I keep one (non-X) console logged in as root. It sits there most of the time doing nothing but it answers these sort of issues. You can also script your unmounts and give them root perms. Or you know well it seems how to manage permissions, so, as Capt. Jean-Luc Picard has been known to say "Make it so!"