Submission source missing

[cubercsl]

Description of the problem

Related to #3031.

If a team submits the same code in two submissions, this page will display nothing.

While this rarely happens, my contest dumps show it happening quite often towards the end of the contest.

In demoweb, since all the code is removed, this problem can be reproduced.

[meisterT]

I was hoping 3957fcd recently fixed it, cc @brinky

[cubercsl]

I was hoping 3957fcd recently fixed it, cc @brinky

Yes, this commit does fix part of the issues (at least it shows the download and edit buttons). I can only view the source code by clicking the edit or download buttons, but it still doesn't make sense.

Similarly, if jury edit and resubmit the same code (i.e. no diff with original submission), will produce similar results.

[Kevinjil]

I would say this is not a bug, but currently intended behavior: we are on a page to show the diff and there is none. I came across it when working on #3058, and have some ideas to improve the UX/UI.