Exporting a problem with a custom validator produces invalid ZIP: custom output validator is missing

[nickygerritsen]

Description of the problem

When downloading the ZIP of a problem with a custom validator, we write to the problem.yaml:

validation: custom

But we do not add the custom validator files to the ZIP file.

We also write:

special_compare='circuitdesign_cmp'

to domjudge-problem.ini. We need to make sure this doesn't hurt (but looking at the code it seems to overwrite this with a custom validator if it comes in the ZIP)

Your environment

DOMjudge version: f79b0c7

Steps to reproduce

Download the ZIP for problem C from nwerc18 from demoweb and try to import this again on a different instance.

Expected behaviour

Problem gets imported correctly.

Actual behaviour

You get an error: Custom validator specified but not found.