Debian unstable/testing as well as the latest debian stable release have a patch to the debian-common script which requires
usr-is-merged on anything that's not an older known Debian release..

Which breaks using that debootstrap for any derivative distribution with a different codename, which is rather unfortunate as that's a reasonable common usage.

Without changing debootstrap we have the following options:

• Make the debootstrap script argument configurable #16 - Making the debootstrap script configurable.. While that would give an escape hatch, it will require using a different
  script entirely as the offending code is in debian-common
• RFE: support using mmdebstrap (instead of debootstrap) #127 - Support another bootstrapping tool; That won't fix current recipes unless it's done as a drop-in replacement. But switching
  the bootstrapping tool underneath the user opens a whole other can of worms. And really i'd like to avoid having to
  support multiple tools, even with all its issues debootstrap is still the official bootstrapping tools
• actions: debootstrap: Expose include and exclude arguments #358 - Expose debootstraps include and exclude options; Which we avoided thusfar as debootstrap really isn't the right location
  to add more packages (use apt actions for that) or to remove package as that's risky as well. When using a minbase
  variant the latter really shouldn't be needed. Not unsurprising it was only proposed due to this issue. And ofcourse, this
  still requires users to switch their recipes so it's quite annoying.

TL;DR we can't have nice things; and in particular all these options require users to chagne their recipes which is really not great