Comment 25 for bug 1928075

After being set up in the broken way we can run the test more quickly

$ sudo chroot /home/ubuntu/bullseye-arm64 /bin/sh /debootstrap/debootstrap --second-stage
$ tail -n 1 /home/ubuntu/bullseye-arm64/debootstrap/debootstrap.log

This is repeatable and will as last line contain:
good case:
 duplicate value for 'Package' field
bad case:
Segmentation fault (core dumped)

That can be used in a git-bisect script,

Due to "fix_binary" in binfmt we need to replace the interpreter after build.
Otherwise it will use the installed one even if overwriting the file in /usr.
#once
$ sudo update-binfmts --unimport qemu-aarch64

Then on each loop:
$ sudo update-binfmts --remove qemu-aarch64 /home/ubuntu/qemu-aarch64-static.test
$ sudo update-binfmts --install qemu-aarch64 /home/ubuntu/qemu-aarch64-static.test --magic '\x7f\x45\x4c\x46\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xb7\x00' --mask '\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff' --fix-binary yes --credentials yes
$ sudo update-binfmts --display qemu-aarch64

Checking if v5.0 and v4.2 behave as expected - with the above they do (one works, one fails)

Started bisect and will come back later ...