bug(?): Approved extension removes the "available until" date.

[wi-chan]

Approved extension removes the "available until" date. That would allow the student that has an approved extension to submit an assignment (with a late status), after the intended accepted late date.

I think the correct behavior should be, when an extension is approved, the "available until" date stays the original "available until" date or the approved extension date, whichever is later.

steps to reproduce:

1. set assignment with due date of 10/31/2025, and available until date of 11/14/2025
2. student request extension for 11/7/2025
3. Looking at the assignment on bCourses, the available until date for that student is missing.

[cycomachead]

Thanks!
This does seem wrong.

One question on behavior overall: Should both the due date and the available until date shift by the same amount, or should the assignment simply be available until the extended deadline?