Soren, Niels, thank you both for your feedback!
I've pushed an update to the markdown package on Mentors, where I've
split the single big debian.patch into six different well documented
patches, and also added back Rules-Requires-Root while keeping the
build-dependency on dpkg-build-api (= 1). I'll watch closely for Policy
updates, waiting for the day I'll be able to remove this odd thing
I have to copy-paste in all my control files :)
Let me know if there's anything else you think I should fix! As always,
you can find the package on both Mentors[1] and Salsa[2].
Bye!
[1]: https://mentors.debian.net/package/markdown/
[2]: https://salsa.debian.org/tachi/markdown
