Test mismatching testdata #3811

Job	Run time
Backup process	3m 6s
Formatting	1m 31s
Linter	2m 13s
Compile Scss	1m 30s
Build nix environment on MacOS	2m 53s
MyPy	1m 33s
Render Html pages	1m 52s
Test + Coverage	2m 47s
Test if testdata is up to date	2m 13s
Test (shuffled order)	2m 32s
Test Typescript	1m 58s
	24m 8s

Provide feedback