- implements the same as debootstrap in
https://salsa.debian.org/installer-team/debootstrap/-/merge_requests/71
- builds a temporary usr-is-merged package and upgrades to the real one
- create merged-/usr chroots for unstable and testing (which will
become Debian 12 Bookworm)
- add a dedicated merged-/usr section to the manual page
- multiple individual shell scripts instead of one 3.5k line monster
- tests driven by Python script allowing:
* declarative test description in coverage.txt
* collecting errors instead of aborting on first error
* skipping tests
* running specific tests