The only reverse dependency for this package is golang-cfssl (also from cloudflare).
Upstream never issued a release for redoctober. Hence we could just assume that redoctober is part of golang-cfssl's codebase, keep it embedded in golang-cfssl, and stop packaging it separately like we do now. That would solve the FTBFS, since the part of redoctober that is embedded in cfssl doesn't need systemd-go (which is causing the build failure mentioned in this bug). Otherwise we wait for upstream to update its embedded copy of systemd-go, but I have no idea how long it will take. Their copy of systemd-go is 2 years old. Last commit on redoctober was 6 months ago. I don't expect anything to happen anytime soon. Cheers, Arnaud