Description

Steps to reproduce:

1. Go to https://wikifunctions.beta.wmflabs.org/wiki/Z10058
2. Open details tab

Observed behavior:

• All tester-implementation combinations fail.
• If you look at the Network tab in Chrome, you can see the perform_test call never returns.

Expected behavior (Acceptance criteria):

• You can have lots of testers and implementations without this issue occurring

Completion checklist

• Before closing this task, review one by one the checklist available here: https://www.mediawiki.org/wiki/Abstract_Wikipedia_team/Definition_of_Done#Front-end_Task/Bug_Completion_Checklist