This test exhibits flaky behavior. Fix it.

Example fail:
assert 'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8' in {'*MISSING_VALUE*', 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8', 'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7', 'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/png,image/svg+xml,*/*;q=0.8'}