There seems to be a bug in the new assignment module, tested in Moodle 2.3.2+

Description to reproduce the issue:
1. Go to a new assignment module
2. Click on "View/Grade all submissions"
3. Click "grade" for any student
4. Leave feedback and upload a feedback file (tested with drag and drop upload enabled)
5. Click "Save and show next"

Expected result:
The feedback files area is clear (doesn't contain any file).

Actual result:
The feedback file area shows the feedback file that was uploaded for the previous student.

This is quite a significant because it is possible that lecturers accidentally e.g. send a completed assignment with lecturer notes to the wrong student.