IMO the bug is not in dracut, but only in sicherboot. >From the control file: This package diverts the /etc/kernel/postinst.d/dracut file and replace it with its own file that calls the diverted one before running sicherboot, as dracut does not support any form of hooks. dpkg is not entirely happy with that and asks you if you want to replace a "deleted" dracut conffile - answer yes.
I will try so solve this with the maintainer of sicherboot during DebConf. -- regards Thomas