This issue derives from
SAK-2077, "Assignments Option for Automatically Accepting Resubmissions". That issue describes a list of desired features for allowing Assignment revisions, automatic submission of assignments, resubmissions, and batch changes of resubmit preferences from a list of students.
This patch addresses a limited scope of the original issue, the ability to allow students to upload revisions before the Assignment due date. It modifies BaseAssignmentService, AssignmentAction, and related screens to permit an instructor to indicate that an Assignment will allow revisions. There is no numeric limit on the number of revisions allowed, and the default end date is the Assignment close date.
The Submissions screen still shows a checkbox to permit resubmissions, but if the Assignment is created to allow revisions, it overrides the ability to disallow resubmissions.