should test cases be included in this PR or should that be handled upstream

Ah this is fine as-is, it's more-or-less well-tested already and relaxing to bytes I think is reasonable to have without a test.

has there already been discussions about their similarity and possible reuse?

nope, just some old code and you're witnessing how things evolved over time :)

If you'd like to help clean up with a PR that'd be much appreciated!