CCX: unenrolled students still appear in Student List Management control

[pwilkins]

When I unenroll or revoke access for a user in the CCX Enrollment tab, the user's name remains in the Student List Management control even though the CCX is no longer available in the user's dashboard.

1. As Coach revoke access of a CCX student.
2. Verify that the student's name remains listed as an enrolled student.
3. As the student, verify that the CCX is no longer in your Dashboard.

[tssheth]

As mentioned in #78 (comment).

[tssheth]

I saw this issue again on today's deploy on sandbox2o. I attempt to revoke access using "Student List Management" but the student still has access to the CCX and the student is still listed. "Adding students" does not seem to work on "Student List Management".

Also, Batch Enrollment continues to be functional. However, unenrolled students appear in Student List Management.

[tssheth]

The CCX coach can now "add students" and "revoke access" using "Student List Management". Unenrolled students appear in "Student List Management".
https://github.com/edx/edx-platform/pull/8986#issuecomment-127276550

[pdpinch]

closed via edx#9335