Status code check in REST API tests is broken

[devos50]

It seems that after merging #6206, the status code check in the REST API tests is broken (see here for the code change). The check is currently as follows:

assert expected_code, response == status

However, this is merely checking whether expected_code is true (i.e., non-zero), and if the assert fails, it will print response == status as the reason. We should fix this logic.