Redmine

In Redmine 1.2.0, there are issues visibility setting in "Administration" -> "Roles and permissions" with three options.
All issues
All non private issues
Issues created by or assigned to the user

Assume in a project we create a new role as "External users" and grant this role the issues visibility as "Issues created by or assigned to the user".
The expected behavior should be like that external users can only view the issues created by themselves or assigned to them no matter the issue is public or private.

While the fact is that if the issue is created by internal users and not assigned to external users,
If it is public,
it will still be viewed by external users in issue list, just can not view the contents of that issue.
If it is private,
it will not be displayed for external users even in issue list.

It seems that it makes no sense to let external users see the issues in issue list which he/she can not view the contents, even it is a public issue.

Can it be unified as the second behavior?
Hide those issues "not created by or assigned to" external users in "Issues" tab for them?