I have noticed a strange issue with collaborative storage policies
linked to edirectory groups. I have a shared storage folder, with a
number of sub-folders. Most of these sub-folders have trustees -member-
and -owner- but one has just -owner- as the trustee.

If the owner is removed as a member of the group, but is left as the
owner of the group, then that person's trustee rights to the -owner-
only folder disappear.

The reason the person is being removed as a member but not as an owner
is that the process is automated. I'm in a school and the groups
represent faculties. People become members of the faculty if they teach
at least one class in the faculty. If they no longer teach any classes,
they are removed as members. At change of semester, staff lose all
their old classes, and hence get removed from faculty groups, then gain
the new semester classes and get added again. But the end result is
that the head of faculty ends up without access to "faculty head" folder
and I have to run an apply membership to reinstate the correct rights.

Is this a bug or a feature?