Scap has an unconventional test runner setup, where a script (scripts/check) runs several test and check tools based on what's installed on the system. Tools that are not available are silently skipped. In CI, those are run in a Docker container with dependencies to install declared in test-requirements.txt and in the Blubber image definition.
One of those checks is formatting with the black autoformatter. However, black is not installed in the Docker environment and so has been silently ignored by the test suite for ages. The result is that running scap's check script in an environment with black installed results it complaining about several thousand lines (about 2k added and 1k removed as of time of writing). This is not ideal, so the check should either be fixed (preferred by the task author) or removed.